HOW TO CUT,GRIND, AND POLISH STONES EASY TO UNDERSTAND - YouTube HOW TO CUT,GRIND, AND POLISH STONES EASY TO UNDERSTAND Want to watch this again later? Sign in to add this video to a playlist. Need to report the video? Sign in to report inappropriate content. Rating is available when the video has been rented. This feature is not available right now. Please try again later. Uploaded on Nov 19, 2011 I AM SHOWCASING MY SKILLS WITH STONES AND GEMS, I AM A JEWELER AND LAPIDARIST . I TRAVEL TO SMALL SHOWS AND SELL MY WORK, I ALSO DO CHEMISTRY, ELECTRICAL ENGINEERING IN MY ART Category Lapidary LAPIDARY Click on the pictures below to jump to a larger version... LAPIDARY (STONE CUTTING AND POLISHING) The working of stone is perhaps one of the most ancient of all crafts and has been an attendant 'work' of mankind for thousands of years. Stone was worked into tools for cutting long before metal even appeared on the scene - Flint and Obsidian are famous examples of stone fashioned into cutting implements and weapons.

Minerals, especially the softer and more colourful, have been used for decorative purposes, either as an article in its own right, to it being ground into powder to make paint. These uses for stone predate recorded history. Later, stone was used for decorative items and was shaped and polished for jewellery, ornaments, and much else besides, examples of this use of stone appears all over the historical record. Today, stone, and stone jewellery are ubiquitous. It has been said that if Earth was ever under observation by extra-terrestrials, humans would be noted for their prediliction with two things - fornication, and shiny objects. This page is an account of my fascination with the latter. Lapidary is the craft of cutting and polishing stone. Strictly speaking the name for this craft would be applied to precious stones and jewels, but in a wider sense it includes semi-precious stones as well. It is the latter type of stone that is the topic of this page. At this point it is worth telling how I first became interested in this curious hobby... Back in 1994 I visited the South Atlantic islands of Ascension and St.

Helena, two small volcanic islands that stand in stark isolation among that great expanse of sea. While staying on Ascension I was asked if I wanted to find some Obsidian. I hadn't the faintest idea what that was but went along anyway. It turned out to be a type of volcanic rock - glassy, black, scattered about in a few parts of the island. I collected a few pieces and that was the end of the matter for a few years. However, during that visit I purchased a visitors guide to the island and reading it again a few years later I noticed a small remark about that stone. The book stated that it could be polished and was noted for its lustrous finish. While of no real value the stone nonetheless could be made to take on an a very attractive appearance. Fast forward to 1999 and during a second visit to the island I decided to revisit the part of the island where that type of stone could be found. Now knowing what to look for I picked up several small fragments and brought them back home with me. Bearing in mind the comment about polishing Obsidian I decided to buy a small kit when I got back to the UK.

This kit was a starting pack which comprised a machine, drums, grit, and an assortment of stones - everything needed to kick-start what has become a hobby that has occupied me for over 7 years. THE MACHINES The machines I use are simply a small electric motor that drives a pulley via a belt. The pulley turns a roller which sits on top of the machine. A free-wheeling roller runs parallel to that and it is on these rollers that a drum sits (and revolves) when the machine is switched on. The picture below shows one of the 4 machines that I use, all are identical. They have all been rebuilt to incorporate improvements on the original design - they are fitted with different bearing blocks and use an 'O' ring as a drive belt. The re-designed bearing blocks are made of a self-lubricating plastic/nylon and are harder wearing than the original. The 'O' rings are used since the machines then require no belt adjustment and are cheaper to replace. Typically, the belts last 9 months and replacement takes seconds. Each machine motor is rated at 15 watts so although they are in near constant use they do not consume much electricity. The machines turn the drums at about 45rpm.

That works out at about half a million revolutions a week! A recent calculation showed that each machine consumes less than 25 pence worth of electricity a week. (Click on the picture below to see a larger version. Use the 'Back' button on your browser to return to this part of the page.) DRUMS The drums are made of rubber with a screw down lid. It is into these drums that a quantity of stones and grinding medium are loaded, the loaded drum then being placed on the machine. At one point I used to use plastic drums as supplied with the machines but I found that these wore out quickly and were noisy in use. The drums shown hold a load of 2 and a half to 3 pounds of stone (1kg to 1.5kg) depending on the density of the stones. Also, the size of the stones loaded varies along with the weight. A single stone up to 3 and a half inches in diameter could be accomodated in one of the drums, or many more smaller stones. The picture below shows the type of drum that I use for grinding and polishing stones.

Click on the picture to see a larger version of it, use the 'Back' button on your browser to return to this part of the page. The whole process of stone tumbling and polishing (as I do it) involves 3 separate methods, 4 if you include breaking and cutting. Read on... BREAKING STONE Some stones are simply too big to tumble and in this case I may resort to what could be seen as brutality. One of the simplest ways of breaking a stone is to hit it with a hammer. The only trouble with this is that splinters tend to fly off. To get round this I wrap the stone in a piece of cloth. A bit of controlled violence can quickly render a stone into much more managable pieces. The disadvantages of this method is that although the stone can be broken up there is little control over the shape of the stone. Also, hitting the stone tends to introduce small cracks which can spoil parts of the resultant smaller stones. Lastly, it can generate a lot of splinters which are in effect wasted stone. At other places on this page I mention cutting and grinding... Some stones destined for polishing can be quite large and may require breaking up.

In other cases a stone may have cracks or other defects that would spoil an otherwise nice looking stone. Lastly, it may be that a stone has to be shaped. CUTTING STONE When a stone requires treatment prior to tumbling or polishing I set it aside for cutting and grinding. For this I have adopted what may be an unconventional use for a tile cutter. At various outlets one can buy what is basically a circular saw blade, diamond-tipped, which rotates at right angles to the machine's table and protrudes above it. (Think of a circular saw table for cutting wood and you have general idea.) Below the machine table is a small water reservior; the water acts as a lubricant and coolant. Set in motion the diamond blade spins up and now offers a very powerful cutting and grinding tool. As you may know, diamond is the hardest substance known to man, so what you now have is a tool that will cut any stone. Not only that but the side of the cutting blade is also diamond-coated so not only can the machine be used to slice a stone it can also be used to grind the surface of a stone. This means that almost any stone can be cut and ground to a desired shape and size.

I often use the machine to deliberately shape stones but it must be said at this point that the cutting and grinding process has a couple of drawbacks. It is both noisy and messy; Noisy to the extent that I always wear ear defenders - not the ideal machine to use at midnight; Messy in so much that the machine tends to generate a lot of water spray while in use. One final drawback is that as some stones are cut small fragments are liable to fly off in all directions - safety goggles are a must! These machines are really designed to cut ceramic tiles and the like but they are quite effective on stones (which are invariably much harder and more difficult to cut than a tile). The advantage of processing stones this way is that cracks, splits, indentations, and other flaws in a stone can be rapidly removed. For example, a cracked stone could be cut along the crack resulting in two smaller stones but ones which after cutting will have no flaws; A stone could be purposely cut and ground into a specific shape to make a pendant; A small peak or indent in a stone could be ground off to produce a flatter surface suitable for subsequent tumbling and polishing. GRINDING STONE The advantages of cutting and grinding are numerous.

Apart from being able to control the shape of a stone it can also save time - a small pip of stone could take weeks of tumbling to remove with the resultant loss of other parts of the stone as well. In some instances I have cut and ground a stone and after as little as 2 weeks of coarse tumbling it is ready for the later stages - otherwise it could take 10 or more weeks! In practice, small stones, down to about half an inch size, can be processed this way. Anything smaller and I'll either let the tumbling processes take care of the stone, or work on it with a small diamond grinding point and electric drill. In many cases this cutting and grinding is done before the next stage... One of the problems with the cutter I use is that the diamonds on the wheel are quite large and the finish they leave can be quite rough. The cutter is ideal for rapid work but lacks finesse. For finer work, shaping, flat surfaces, smooth curves I use flat lapping discs. These are flat steel discs coated with various grades of diamond, the discs I use are six inch (150mm) diameter.

These are mounted in a vertical drill press, cooling and lubrication provided by a drip feed of water and a tiny amount of liquid soap. Use of these laps is much quieter and less messy than the cutting machine and allows fairly precise grinding of stones held by hand, even if using a coarse lapping disk. I use 6 grades of lapping disc: 100, 280, 600, 1200, 3000, and 50,000 grit. Use of the first two, coarser grades, is surprising fast at smoothing stone and can allow a stone to miss the coarse tumbling stage completely. Exceptionally flat and/or smooth and/or curved surfaces can be ground with these laps. With patience and care it is possible to grind facets onto a stone as well. Moving onto the finer grades prepares the stone for polishing, done with the 50,000 (0.5 micron) grit lap. With these discs it is possible to hand work stones into shape and polish them in as little as 20 minutes.

Larger or more complex shapes take longer but a rough time is about an hour from start to finish - a tiny fraction of the time taken by tumbling - and with complete control of the shape and degree of finish. STAGE 1 - COARSE TUMBLE AND GRIND This is where a quantity of stone is loaded into a drum. Added to this is a small amount of 80 grit silicon carbide and the stones are then covered with water. A small amount of air is left at the top of the load. These quantities have to be fairly well judged - too little stone and the excess space means that the stones smash each other - too much and the stones don't grind against each other. Too little grit and the stones don't wear down. Too much grit and some will be wasted. This mixture of stone, grit and water is then sealed inside the drum and the drum put on the machine. This load will then tumble for about one week. After a week has elapsed the machine is shut down, the drum lid removed, and the contents put into a sieve and washed. The resultant slurry, a mixture of ground stone, grit, and water, is washed away.

It is often worth removing the stones from the drum by hand since this will leave the slurry in the drum. This slurry can be allowed to settle, the water drained off, and the sediment checked. In some cases grit is left behind and this can be left in the drum for future use, saving money in the long term. Depending on the hardness of the stones in the load it may be necessary to go through this process many times, up to 10 weeks or more is not unusual if I want good results from stones that are fairly rough and are also quite hard. Once the stones have been washed and dried they have to be inspected for any flaws or cracks. Any that are defective will have to go through Stage 1 again. Before any progress can be made the stones must be smooth and free of defects before they are ready for Stage 2. Very smooth stones and other well rounded, smooth stones may need only a few weeks going through Stage 1 but jagged and other badly flawed stones could take months to smooth so I often set aside badly flawed stones for cutting and grinding. In many cases some stones destined for polishing have to be broken up in this fashion before it is suitable for the coarse grinding process.

(Many 'offcuts' are quite attractive in their own right and a selection of small stones, all of which are offcuts, can be seen further down this page.) After several weeks of Stage 1 stones start to emerge that are suitable for the next part and if enough are ready to correctly load a drum I can then go onto Stage 2... STAGE 2 - FINE TUMBLE AND GRIND Although I say 'Fine Tumble' this stage is often referred to as a 'Pre-polish'. Stage 2 is similar to the first except that 400 or 600 grit Silicon Carbide is used instead. Stones going into a drum must be washed thoroughly to exclude any trace of the coarse (80) grit. The drum and its lids must also be removed and thoroughly cleaned to remove any trace of the 80 grit. Having said that, I tend to reserve a drum specifically for this stage, this further reduces the chance of grit cross-contamination. The picture below shows the three different abrasives I use. At left - 80 grit Silicon Carbide; Centre - 400 grit silicon carbide; Right - Cerium Oxide powder.

The ruler used for scale gives some idea of the size of particles. The 80 grit is a tad smaller than typical sand grains and the Cerium Oxide is much finer than talcum powder. (Click on the picture below to see a larger version. Use the 'Back' button on your browser to return to this part of the page.) In some respects Stage 2 is the most important process of all. The loading of the drum is critical: As in the first stage too little stone will mean that the stones bang against each other but too much will mean that the stones don't tumble and grind against each other. With Stage 2 I leave the machines to turn the drum for at least 10 days. Since most of the grinding and polishing process I do is based around a weekly cycle I often leave a fine load to tumble for 2 weeks. Even though Stage 2 is still a grinding process the 400 grit Silicon Carbide is very fine and after 2 weeks of grinding the grit has broken down into much smaller particles, probably in the order of 1200 grit or finer.

(Those of you familiar with the likes of sandpaper or wet and dry paper will know that 1200 is pretty fine stuff.) Like Stage 1, the load is washed and cleaned after its cycle and the slurry washed away. By the end of this stage some stones will have attained great smoothness with a dull satin finish. They should now be ready for the last part - polishing. STAGE 3 - POLISHING As before, the stones must be thoroughly washed and dried before this final stage. I reserve a drum each for Stages 2 and 3 to reduce the chances of cross contamination of grits and polish. The same load that came from Stage 2 can be put straight into the polishing drum after cleaning. In this stage the polish used is a very fine pink powder called Cerium Oxide. When I say fine, I mean that the particles of polish are about typically less than 3 microns in size (about 8000 grit), that is, 3 thousandths of a millimetre!

This powder is quite expensive but one bonus is that it can be used over and over again, it is not necessary to wash away the slurry or clean the barrel unless a stone has broken during the polishing cycle and fragments are impossible to exclude. The stones are tipped into a sieve held over a bowl so that the water/polish mixture can be saved for future use. Lately I have started using Tin Oxide as a polish, so far with excellent results, if anything better than Cerium Oxide although the jury is still out on that one. In some cases, to pack the drum to help prevent breakage I use plastic pellets as a packing medium. The pellets tend to fill in small gaps between stones and generally smooth and aid the tumble polishing process. I have found however than the pellets can slow down the polishing cycle and nowadays I prefer to use small Flint pebbles that have already been polished. Even after 2 to 3 days some stones will already have a nice finish but since I tend to time everything on a weekly basis I leave the stones to polish for a week. This usually ensures that when I shut down the machine and check the stones they have all attained a very high polish.

My most recent addition to polishing techniques is the use of diamond powder. I've experimented with 14,000, 50,000, and 100,000 grit diamond powder with a polishing load - the results were stunning! I found that 50000 grit, just a single gramme of it, was enough to render a superb polish on stones in just 3 days. Cerium oxide or Tin oxide loads for 3 pounds of stone in a drum typically weighs about 15-20 grammes, several orders of magnitude more than the apparent diamond quantity needed. Other polish techniques used over the last year or so include hand polishing. For this I use a 12 inch (300mm) piece of smooth plywood with a sheet of Chamois leather stretched over it. I then sprinkle a small amount of polishing powder (Tin oxide or Cerium oxide) onto the centre of the sheet and then work the stone back and forth by hand. This is quite effective for flat surfaces and with patience any convex surfaces. For speed and quality I use a similar technique but with a leather covered disc loaded with polish set-up on a drill stand.

The stone is then held onto the disc. Some stones, particularly soft stones, do not always respond well to tumble polishing and this method will often yield satisfactory results. Another method which works very well for soft stone like Malachite is the use of cotton mops. These are round discs of stitched cotton which can be set up on a drill. Closed stitched mops and Tripomax (brown) polish, and then open stitched mops and Superblue (blue) compound for the final glossing, will yield very pleasing results on soft stone. These last stages are the most rewarding of them all. Carefully selected, loaded, washed and inspected stones are completely transformed by weeks, months even, of the machines going constantly. On the other hand, individual stones can be worked by hand on lapping discs and then polished in under an hour. Whatever the method, as you will see in the next section of this page, the results are often stunning... POLISHED STONES There now follows a series of photographs of some of the stones that I have polished. Each photo (bar the last one) shows a yellow 1 inch square to give some impression of size.

With every photograph, click on the picture to see a larger version, use the 'Back' button on your browser to return to that part of the page. In all cases the polished stones shown below have been purchased or otherwise obtained as 'rough rock' and then processed myself. In most cases the stones shown are between 10 and 50 grammes in weight although several stones I have polished fall well outside these limits. All the stones shown I have cut, ground and polished myself. The final photograph shows an arrangement of various stones, all of which are offcuts. AGATE (various types) ASSORTED OFFCUTS FINALLY... So, in the previous section of this page you will have seen some of the fruit of many months of patiently waiting for the machines to do their work. The above photos are but a tiny selection of the stones that I have polished since I first started the craft. I'm sure you'll agree that the results are pleasing to the eye. I have reached the stage where I still have a great deal of interest in the craft to continue polishing stone - but have little room to store the stuff!

So, most stone currently on the go is destined for other people as gifts, or for sale, as well as stone that people have asked me to process. In this last respect I am happy to work stone for people upon request. Drop me a line for details. So, there you have it, a rather unusual hobby and some of the results. If you have any questions about this page please do drop me a line, I'd be happy to try and answer your queries. Derek Haselden LINKS I have a large selection of tumble polished stones are available for sale, to take a look at what is on offer click here . About 90% of the stone I have purchased and subsequently polished (or otherwise) was ordered from Mineral Craft North Limited . They supply a great variety of rough rock, polished stones, stone shapes, and other stone jewellery items, as well as stone tumbling supplies. They have another website at Mineral Craft North Limited . Eternal Tools supply a large range of diamond products. I use several products from them including diamond drills, lapping discs, diamond powder and paste. Some grinding and polishing equipment I use was purchased from Axminster Tools.

ï¿½ Derek Haselden 2012 Stone cutter/lapidary Stone cutter/lapidary Sarah Marten 29 November 2012 A stone cutter, also known as a lapidary, cuts, shapes and polishes precious and semi-precious gemstones. This 22ct gold plated silver 'cave treasure' ring designed by Ruth Wood contains cubic zirconia stones with facets cut into them. Image sent What do stone cutters (lapidaries) do? Stone cutters often specialise in coloured gemstones. These could be anything from emeralds, sapphires and rubies to amethyst, rock crystal and black onyx. These stones are then used to make jewellery or decorative objects. As well as cutting stones for new pieces of jewellery, lapidaries also repair and re-polish jewellery stones, often from antique pieces. They may also repair the stones in other antiques, such as stone-inlaid clocks, urns and goblets. What is the job like?

As a lapidary, your job would involve: using a magnifying lens to examine the stone for fissures, holes and cracks cutting the stone into the required shape, such as a block, or slicing it using various saws and grinders with diamond-blade edges. The diamond may be applied manually, or the machine may have an electro-plated diamond-blade edge using a faceting machine to cut the stone at certain angles so that it catches the light drilling holes in specific places using hand and machine tools to sand the gem in several stages to produce a very fine surface using different types of polishing equipment to finish the stone. You would need a detailed understanding of the different types of gems and their properties, such as the various grains, to enable you to cut the stones properly. Stones vary in their hardness and heat sensitivity, and some are more prone to breaks or cracks. Some lapidaries are employed in jewellery workshops, whilst others are self-employed and make bespoke jewellery for clients. How do I become a lapidary?

If you want to become a lapidary, you need to be: a creative person who loves to make things and who enjoys working with their hands interested in gemstones, and stone generally extremely patient and meticulous willing to work hard and take pride in your work. If you are self-employed, you will normally be working on your own all day, so it's important that you enjoy working independently. Teamwork skills are important if you are employed in a workshop with other people. Relevant school subjects include GCSE Design and Technology and GCSE Art, and an interest in jewellery and gemstones is important. What training and qualifications do I need? Training is normally on-the-job with an experienced lapidary. At present, there are no full-time courses dedicated to lapidary in the UK, although other jewellery courses may include it alongside other aspects of jewellery-making. An in-depth knowledge of gems and their properties is vital for this work. An in-depth knowledge of gems and their properties is vital for this work. The courses run by the Gemmological Association of Great Britain (also known as Gem-A) would provide a good background in this respect. However, they do not cover the craft of stone cutting as such.

Holts Academy of Jewellery offers an apprenticeship in jewellery manufacture at levels 2-4 for those aged 16-23. The apprenticeship combines on and off-the-job training in a wide range of jewellery skills to include stone cutting. You will learn traditional and modern techniques alongside a master craftsperson. There are no formal academic entry requirements, although you will need a keen interest in jewellery, and GCSEs at grade C or above are an advantage. Holts Academy also offers the Diploma in Jewellery Manufacture at different levels, which cover all aspects of jewellery design and making at increasing levels of complexity: Level 2 – this course takes four months, two days a week, with no formal entry requirements other than a keen interest in jewellery making Level 3 – this course takes six months, two days a week, and entry is with a level 2 qualification (above) or experience in the jewellery industry Level 4 – this course takes seven months, two days a week. This is an advanced course, and you will need a level three qualification (as above) or appropriate industry experience. Finally, Holts Academy offers short courses in lapidary .

These cover faceting, carving and basic cabochon cutting (a cabochon is a gemstone which is smooth rather than faceted). You may find short courses in lapidary being offered around the country, usually by private training providers. What can I earn? The minimum wage for an apprentice aged 16-18 is £2.68 per hour, although some employers pay more than this. Once you have completed your apprenticeship, you can expect to earn from around £12,875 per year. With more experience, salaries can rise to around £35,000. The most experienced lapidaries can earn in excess of £35,000 per year. Some lapidaries are self-employed, and their earnings can vary widely. Also of interest Cut and Polished Gemstones at AJS Gems Mahenge Spinel Rough Stone, Tanzania The process of cutting and polishing gemstones is known as lapidary. It is a difficult and tedious process, since gemstone materials tend to be exceptionally hard, with most harder than steel. Gemstones can also be quite valuable, with high quality ruby and sapphire selling for thousands of dollars per carat.

So working with expensive material that can be easily damaged is stressful as well. The first stage in cutting a gemstone does not actually involve any cutting at all. Rather it involves evaluating the material and deciding how to proceed. This takes considerable experience and a good eye, since evaluating rough stone is more difficult than evaluating a finished gem. The first thing to determine is whether the material is sufficiently transparent and clean to cut a faceted gem ; if the clarity is not good, a cabochon will be cut instead. If the material is facetable, the cutter has to decide which part of the rough stone to facet, and what shape to cut. Modern Faceting Machine The gem cutter has to be concerned with both economics and aesthetics. Since gem-quality material tends to be rare and valuable, the cutter tries to preserve as much of the rough stone as possible. This is why so many stones are cut as ovals -- gems found in alluvial deposits tend to be oval in shape, formed by the action of water over thousands of years. Once the shape is decided and included material cut away, the rough stone is preformed to the approximate shape on a silicon carbide wheel.

One side of the stone will usually be cut with a flat surface for the large table facet on the crown of the gem. The stone is then ready for faceting. First the gem is glued to a small stick called a dop, using a wax that melts at high temperature. The gem is then held at a precise angle against a horizontal cutting wheel called a lap to cut the facets, beginning with the pavilion (bottom half) of the stone. Modern faceting machines have mechnical arms that provide very precise control of faceting angles, but simpler devices can also yield very good results in the hands of an expert. Amethyst Octagon Cut Once all the facets are cut the polishing begins, a process which is more art than science. The goal is to achieve a mirror-like finish, and remove all tiny scratches left from the grinding process. Various polishing agents are used, including diamond or corundum grit, tin oxide, cerium oxide and chromium oxide. Expert polishers know how to vary the lap speed and pressure and the consistency of the polishing agent to get the best results. The cutting and polishing of colored gemstones tends to be concentrated in a few locations that have a long tradition of mining, especially Thailand, Sri Lanka and India.

Though Thailand is no longer an important mining location, it continues to be the leading center for cutting, treating and trading colored gems of all kinds. Rough stone is brought here from all over the world, and most of the new African gems are cut in Thailand. How are Gems Cut and Polished? How are Gems Cut and Polished? Not required for EPS2 students The process of cutting and polishing gems is called gemcutting or lapidary, while a person who cuts and polishes gems is called a gemcutter or a lapidary (sometimes lapidarist). Gemstone material that has not been extensively cut and polished is referred to generally as rough. Rough material that has been lightly hammered to knock off brittle, fractured material is said to have been cobbed. Rough corundum. All gems are cut and polished by progressive abrasion using finer and finer grits of harder substances. Diamond, the hardest naturally occurring substance, has a Mohs hardness of 10 and is used as an abrasive to cut and polish a wide variety of materials, including diamond itself. Silicon carbide, a manmade compound of silicon and carbon with a Mohs hardness of 9.5, is also widely used for cutting softer gemstones.

Other compounds, such as cerium oxide, tin oxide, chromium oxide, and aluminum oxide, are frequently used in polishing gemstones. Lapidary Techniques sculptures Sawing Sawing a piece smoky quartz. (Warning! Holding rough by hand during sawing can be hazardous to the stone, the saw, and the cutter! Extreme caution is required.) In most gem sawing, a thin circular blade usually composed of steel, copper, or a phosphor bronze alloy impregnated along the outer edge with diamond grit and rotating at several thousand surface feet per minute literally scratches its way through a gemstone. A liquid such as oil or water is used to wash away cutting debris and keep the stone and the sawblade from overheating, which could cause damage to both the stone and the sawblade. Several sizes of circular rock saws are frequently used by most gemcutters: A slab saw, typically 16 to 24 inches in diameter, is used to cut stones of several inches thickness into relatively thin slabs (often 1/8 to 3/8 inch thick).

A trim saw, typically 6 to 10 inches in diameter, is used to cut smaller stones into thin slabs or to cut small sections out of slabs. A faceter's trim saw, typically 4 inches in diameter, is used with a very thin blade, to saw small pieces of expensive rough. There are also jigsaws that employ either a reciprocating wire or a continuous thin metal band. These are useful for cutting curved lines that are impossible with circular saws. They are also useful in minimizing waste on extremely valuable rough material. Back to techniques. Grinding Grinding, usually with silicon carbide wheels or diamond-impregnated wheels, is used to shape gemstones to a desired rough form, called a preform. As with sawing, a coolant/lubricant (water or oil) is used to remove debris and prevent overheating.

Very coarse diamond or silicon carbide, such as 60 grit, or mesh, (400 micron particles) or 100 grit (150 micron particles) is used for rapid removal of stone, and finer abrasive (600 grit - 30 micron, or 1200 grit - 15 micron) is used for final shaping and sanding. Back to techniques. Sanding Sanding is similar to grinding but uses finer abrasives. Its purpose is to remove deep scratches left by coarser abrasives during grinding. Since it removes material less rapidly, it also allows more delicate control over final shaping of the stone prior to polishing. For stones with rounded surfaces, a flexible surface such as a belt sander is often used to avoid creating flat areas and promote smooth curves. Back to techniques. Lapping Lapping is very similar to grinding and sanding, except that it is performed on one side of a rotating or vibrating flat disk known as a lap , and it is used especially to create flat surfaces on a stone (as in faceting). Laps are often made of cast iron, steel, or a copper-bronze alloy, but other materials can also be used. Back to techniques.

Polishing After a gemstone is sawed and ground to the desired shape and sanded to remove rough marks left by coarser grits, it is usually polished to a mirror-like finish to aid light reflection from the surface of the stone (or refraction through the stone, in the case of transparent materials). Very fine grades of diamond (50,000 to 100,000 mesh) can be used to polish a wide variety of materials, but other polishing agents work well in many instances. Usually, these polishing agents are metal oxides such as aluminum oxide (alumina), cerium oxide, tin oxide, chromium oxide, ferric oxide (jeweler's rouge), or silicon dioxide (tripoli). Different stones are often very inconsistent in their ease of polishing, particularly in the case of faceted stones, so gemcutters are often very inventive in trying new combinations of polishing agents and polishing surfaces -- often tin, tin-lead, lead, leather, felt, pellon, wood, or lucite laps for flat surfaces such as facets. Rounded surfaces, such as on cabochons, are often polished on felt, leather, cork, cloth, or wood.

Polishing removes small quantities of stone and can be used, especially when faceting small stones, to do ultrafine shaping of the stone. Back to techniques. Drilling When a gemcutter desires a hole in or through a gemstone (e.g., a bead), a small rotating rod or tube with a diamond tip, or a slurry of silicon carbide and coolant, is used to drill through the stone. Ultrasonic, or vibrating, drills are also very effective, but they tend to be costly and thus reserved for high-volume commercial drilling. Back to techniques. Tumbling Large quantities of roughly shaped stones are often tumbled, i.e., turned at a slow speed in a rotating barrel with abrasives and water for extended periods (days or weeks). By tumbling with progressively finer grades of abrasive (usually silicon carbide) and washing carefully between grades, the stones are gradually smoothed and polished to serendipitous but often very attractive shapes. Tumbling barrels are often hexagonal in outline in order to enhance the stirring action of barrel rotation. An alternative to rotatory tumblers is a vibratory machine, often called a vibratory tumbler, in which the containing barrel vibrates rather than rotates.

The more stationary arrangement of vibratory machines makes it much easier to examine the progress of the stones inside, whereas standard tumblers must be halted in order to check progress. In addition to polishing gemstones, tumbling is often used to polish large quantities of metal jewelry. Back to techniques. Cabochons One of the simplest lapidary forms is the cabochon, a stone that is smoothly rounded and polished on top, relatively flattish, and either flat or slightly rounded on the bottom (which may be either polished or sanded). This form of cutting is often used for opaque or translucent stones, but is also frequently used for transparent materials that contain too many inclusions to yield a good faceted stone. Coloration and patterning provide the major interest in such stones. Cabochon cutting, or cabbing, is often performed by simply holding the stone in the fingers, but it is more commonly done by dopping (attaching with adhesive wax or glue) the stone to a wooden or metal dopstick. This facilitates twirling the stone to form smooth curves and avoid flat areas during grinding, sanding, and polishing.

A typical cabbing machine holds several wheels representing a progressive series of diamond or silicon carbide grit, turned by a common arbor and motor, and a water supply that provides a coolant/lubricant to wash away debris and keep the stone from overheating as it is ground and sanded on progressively finer wheels. Back to forms. Faceted Stones Faceting is most often done on transparent stones. Flat facets are cut and polished over the entire surface of the stone, usually in a highly symmetrical pattern. The stone is dopped (usually with adhesive wax, epoxy, or cyanoacrylate glue) on a metal dopstick, which is then inserted in a handpiece that allows precise control of positioning. The cutting angle is adjusted vertically via a protractor and rotationally via an index gear. The facets are then ground, sanded, and polished on a rotating lap , while water or another liquid acts as a coolant and lubricant. When one side (top or bottom) of the stone is finished, a jig is used to transfer to the stone to a dopstick on the opposing side.

A faceting machine usually employs a motor that turns a lap , a water supply, an adjustable handpiece with index gears and a protractor, and an adjustable mast or platform to hold the handpiece assembly. Most commercially available gemcutting machines employ a mast, but a few employ a platform. Two different styles of faceting machine -- mast-type (left) and handpiece and platform (right). In recent years, innovative faceters have employed techniques such as concave facets, grooves, and combinations of faceting and cabbing to produce new forms in faceted stones. Back to forms. Beads and Spheres Spheres are initially sawed into cubes or dodecahedrons and then ground to shape between two pipes or rotating concave cutters, allowing the stone to rotate freely in any direction to form a perfect spherical shape. As with other lapidary processes, gradually finer grades of abrasive are used to grind, sand, and polish the stone. While beads may be faceted, they are more commonly cut and polished as small spheres and then drilled to allow stringing. Bead mills are used to grind and sand large quantities of beads simultaneously.

They typically employ a grooved lap and a flat lap between which the beads are rolled and worn to shape. After shaping and sanding, beads are usually polished by tumbling . Back to forms. Inlays In an inlay, a gemstone is cut to fit and glued into a hollow recess in another material (metal, wood, or other stones) and then the top ground and polished flush with the surrounding material. Stones most commonly used for inlay are strongly colored opaque stones such as black onyx, lapis lazuli, turquoise, tigereye, etc. Back to forms. Intarsias and Mosaics In both intarsia and mosaic work, small bits of different colored stones are fit together and the top cut and polished to present a picture or other interesting pattern. Strictly speaking, a mosaic is constructed on top of a flat base of another material (usually stone), while an intarsia (also known as Florentine mosaic, or pietre dure) is set flush into the surface of the base material.

The finest intarsias and mosaics were traditionally of Italian origin, but intarsia has enjoyed something of a renaissance in recent years with the fine work of artists such as Jim Kaufmann and Nicolai Medvedev. Back to forms. Cameos and Intaglios Cameos and intaglios are similar in that both usually are carved portraits in stone or seashells. They differ in that cameos are raised portraits, while intaglios are carved down into the surface of the material. Both typically take advantage of different colored layers of material. The finest cameos and intaglios have traditionally come from Italy (usually shell) or Germany (usually agate). Back to forms. Sculpture Gemstones can be carved, like other materials, into almost any form, limited only by the talents of the sculptor. Carving is accomplished with a variety of diamond-impregnated steel bits, saws, and grindstones. Note: the information in this html page has been downloaded with permission from John Miller's excellent gems site. Cochise College P Cutting and polishing a Raw Gemstone HISTORY Where did gem cutting get its start?

In prehistoric times 70,000 BCE man banged and hammered away with his tools of stone, rubbing one stone against another, polishing the stone by using sand, also man chiseled and carved out symbols and primitive writings on hard rock and cave walls. In doing so, man learned the great secret that some stones are harder than others and they are capable of inflicting scratches on other less hard stones. This is how drilling and butting became possible. Drilling was the first of the lapidary arts, and it shows itself as far back as 1,000,000 years ago. In these times people learned that rocks could be broken or fractured. Butting was the shaping of a gem through rubbing one gem against another harder mineral type At one time man compared the smooth polished effect from the stones that came out of a river and a stream. Man concluded that something was bringing a smooth and polishing effect to the stones in these streams. It was believed that other particles in the river working to complement the action of the constantly running water. By 3,000 BC man had developed lapidary skills to such a level that cylinders made of serpentine, were commonly used.

Before Christ, lapidaries had pretty much conquered the challenges of sawing, chipping, drilling, and faceting. The work was crude but there is much work that is still with us today. Photo is from ï¿½The History of Lapidaryï¿½ Many diamond cutters used a small box beneath their manipulations, as in the picture on page one. This was called a butters box to catch the rubbings or diamond dust, whose grit was so tiny it was later used in the polishing process. The technique was used until more refined techniques were introduced. In the 1400ï¿½s was when the breakthroughs went into full swing. Louis de Berquen, of Bruges, Flanders, was acknowledged as the Father of Modern Diamond Cutting, in 1476. His introduction of absolute symmetry, improvements in the polishing process and the development of the pendeloque shape. He developed the horizontally mounted metal grinding wheel (skeif). He covered the metal wheel with diamond dust suspended in oil. The oil, kept the diamond particles on the rotating wheel rather than allow centrifugal force to sling them away.

This led to great advances in polishing technology and control of the stones that had been cut. SHAPES The Bead and Cabochon known as ï¿½Glypticï¿½ was the first gemstone cuts used by man. It was the first choice for jewelry making and ornamentation. These stones were shaped by rubbing them with other stones and polished by using sand as an abrasive. These cuts go back to the 7th millennium. The examples below are some of the early Roman gemstone cuts with several variations of cameo and intaglio. Photo is from ï¿½Lapidary History Early Gemstone Cutsï¿½ A cabochon is a shape that is simply rounded as opposed to a faceted cut. In the 1400ï¿½s, gem cutters were limited to the cabochon, due to the limited technology available. A cabochon is used to describe a cut of a gemstone that is not facetted. When cutting a cabochon, the small amount of light that is able to pass through the stone is due primarily to its crystalline structure and optical qualities.

Cutting a stone cabochon is usually applicable to opaque gems, although transparent semi-precious gemstone can also be cut cabochon cut. Below are some more examples of cabochon cuts. Cabochon cutting, or cabbing, is often done by simply holding the stone with the fingers of both hands. This allows the twirling of the stone to form smooth curves and avoid flat areas during grinding, sanding, and polishing. A typical cabbing machine holds several wheels representing different series of diamond or silicon carbide grit (80, 220, 280, 600, 1200, 14,000) turned by an arbor and motor, and a water supply that provides a coolant/lubricant to wash away debris and keep the stone from overheating as it is ground and sanded on progressively finer wheels. Photo is from ï¿½Lapidary History Early Gemstone Cuts Other types of cuts are facetted cuts, which are usually done on transparent stones. Facetted gemstone and diamond were introduced in European jewelry during the late 13th and 14th centuries.

Flat facets usually in a high symmetrical pattern, are cut and polished over the entire surface of a stone. A stone that is faceted, is dopped, usually with adhesive wax, on a metal dopstick to control the positioning of the cutting angle. The facets are then ground, sanded, and polished on a rotating lap, while rotating water acts as a coolant /lubricant. When one side top or bottom of the stone is finished, the other side of the stone is transferred to a dopstick on the opposite side. In recent years faceters have acquired techniques such as concave facets, grooves, and combinations of faceting and cabbing to produce new forms in faceted stones. Below are some photos of the construction of the gem cutting machine. Next is the model of the gem cutting machine and the image of the diamond cutters engraving using his books in 1694 and using a foot powered cutting wheel. Photo is from ï¿½Gem Cutting &The History of Faceting Gemstonesï¿½ The steps to cutting and polishing a stone are: Marking: A rough stone is always marked to determine the direction of the grain or cleavage.

The natural shape of the stone will be important in deciding how to cut the stone. Cleaving: When a stone is struck along its grains to split it. Sawing: The stone is cut closer to the shape of the finished cut without any facets. When sawing the stone there is water or oil moving at all times to prevent overheating. The sawing can also give stone unwanted fractures. Sawing is when all the unwanted material is removed from the stone to get closer to desired cut. The next page is an image of a saw cutting a raw stone close the shape wanted. Grinding: The stone is on a dopstick or held with the fingers to move around to each wheel. Each wheel has a different grit ranging from 80, 220, 280, 600 grit. This process is for shaping and sanding of the stone. This machine also needs coolant to prevent overheating. Sanding: Sanding the stone is the same process as grinding, but with finer abrasives 1,200 and 14,000 grit. This step is to remove deep scratches. Lapping: Lapping is similar to grinding and sanding.

The process is usually done on a rotating or vibrating flat disk known as a lap, this is to create flat surfaces on a stone. Laps are usually made of cast iron, steel, or a copper-bronze alloy. Polishing: Polishing the stone is done on a felt, leather, cloth, cork, wood, tin, tin-lead or lucite laps. The wheel is wet with a polishing agent such as a metal oxides - aluminum oxide (alumina), cerium oxide, tin oxide, chromium oxide, ferric oxide (jeweler's rouge), or silicon dioxide (tripoli). This is the last procedure and it is to remove any rough marks left by coarser grits. Should I Use Oxide Polish Or Diamond For Polishing Gems? Home » Articles » Jewelry and Lapidary » Lapidary and Faceting Equipment » Should I Use Oxide Polish Or Diamond For Polishing Gems? Should I Use Oxide Polish Or Diamond For Polishing Gems? by Jeff Graham A natural topaz gemstone is usually best polished with aluminum oxide. Under some situations, however, a diamond polish may be used. “Topaz,” 2.08 cts, round brilliant, Pakistan.

© Dan Stair Custom Gemstones . Used with permission. I’m frequently asked by novice gem cutters whether they should use oxide polish or diamond for polishing gemstones. I do have my opinions, based on many years of experience. First, I want to be clear about the type of materials I cut, because your gem types are a deciding factor when you’re choosing an abrasive for polishing. Recommended Polishes For Natural Gemstones I cut natural gemstones almost exclusively. The majority, with the notable exception of sapphire and chrysoberyl , are easily polished with an oxide polish, either aluminum oxide (Al2O3) or cerium oxide (CeO2). Diamond polish tends to work best on hard stones, hardness 8 and above. On softer stones below hardness 8, diamonds are much more problematic. Stones Typically Polished With Cerium Oxide Amethyst is best polished with cerium oxide. “Amethyst,” 7.45 cts, fancy octagon, Brazil. © Dan Stair Custom Gemstones . Used with permission.

Stones Typically Polished With Aluminum Oxide Garnet of all types ( almandine , demantoid , spessartite , pyrope , grossular , uvarovite ), peridot , tanzanite , tourmaline of all types (achroite, dravite, elbaite, indicolite, rubellite , schorl, siberite, verdelite), spinel , zircon . I rarely cut the following, but they should also be polished with aluminum oxide. Stones Typically Polished With Diamond Sapphires (of all types), chrysoberyl, danburite . Exceptions There are some exceptions, depending on the individual stone. In some cases, as stones get larger they may require diamond instead of an oxide polish. Some stone types I occasionally polish with diamond are topaz, zircon, and spinel. Sometimes I use diamond on a problem stone or even a problem facet. I don’t cut synthetic gem material , but most can easily be polished with an oxide polish. However, synthetic corundum and cubic zirconia would require diamonds to polish. Danburite is best polished with diamond.

“Danburite ovals,” concave facets, approximately 6 cts each, Madagascar. © All That Glitters . Used with permission. Working With Oxide Polish Is Faster Than Diamond I prefer to use an oxide polish on almost all my gemstones. I know some experienced cutters prefer to use diamond on various laps (such as ceramic, tin, or copper). To each their own. Polishing can be done in many different ways. Go ahead and try different polishes and laps. However, I’ve found there are various reasons oxide polish works better than diamond polish on most natural stones. I think inexperienced cutters can benefit from this knowledge. It’s been my observation that oxides work faster. Generally, aluminum and cerium oxides leave higher quality finishes than diamond. Many oxide polishes are 0.3 micron or finer, depending on the manufacturer, which is close to 100,000 grit . A typical diamond polish scenario would be to cut the stone to 1,200 grit and then switch to diamond pre-polish and polish.

Generally, the steps would be something like this: 3,000 (for a large stone), 8,000, 14,000 (not always used), and 50,000. Some people may polish to 100,000 diamond, but most don’t go finer than 50,000 on an average diamond polish. A typical oxide polish scenario (for me) is to cut the stone to a worn 1,200 grit lap and then polish with either cerium or aluminum oxide. That’s it. Done. Oxides are one step. A diamond polish is a minimum of two steps, and many stones require 3-4 extra diamond polish stages. Remember, on every step/polish you’ll have to cut/polish every facet on the entire stone. Let’s say you’re dealing with a gemstone that has 100 facets. Depending on the stone and the extra polishing stages you need to set up for a diamond polish, you could be looking at polishing the equivalent of 500 to 600 facets! Think of the hours that four extra diamond polish stages will take.

If your gemstone can be polished with oxides, that’s a better option. Every pro I know, including myself, uses oxide polish extensively. That should tell you something. Of course, I’m not talking about contest gem cutting conditions, where a slow diamond polish is easier to control for meets under high power. However, I would note that many contest stones are “kissed” with an oxide polish after the diamond polish to give them a final “pop.” Lap And Polish Combinations Spectra Ultra Laps For beginners or those who don’t cut many stones, Spectra Ultra Laps are a good, inexpensive choice. They can be charged with whichever oxide polish is needed and work well. If used properly, they will actually polish nice, flat facets. A light tough and a good pre-polish are the secrets that prevent rounding. (I know several guild contest winners that use Ultra Laps to pop their stones before sending them to be judged. Some won’t admit it because they don’t want people to know what they’re doing). Tin Laps A tin lap is an all-around workhorse that performs well with any type of oxide polish.

Once broken in, tin laps polish about as fast or faster than any other lap for garnet and tourmaline. I probably use a tin lap with aluminum oxide the most, mainly because I tend to cut a lot of garnets and tourmalines. Since zinc laps are no longer readily available, I generally use tin laps with diamond polish when necessary. (I use one 8,000 and another 50,000 diamond charged tin lap). Zinc lap Phenolic Laps I’m finding that I like phenolic laps and use them often. They work very well with any oxide polish and are very inexpensive, too. I don’t recommend these for beginners. They can be a little fussy when lining up a facet to be polished. I do recommend phenolic laps for advanced cutters. In most cases, these laps aren’t quite as fast or easy to use as a good tin lap, but I’ve found they help solve some occasional polishing problems. In some cases, they polish as fast and sometimes better than a tin lap. Oxide Polish Is Easy To Use I want to point out one last thing. Have you ever noticed all the people on online forums talking about troubles with their charged diamond polishing laps?

Notice how often they talk about how to clean them, get them to stop scratching, recharge them, resurface them, or fix them in general. Have you ever noticed anyone discussing these troubles with an oxide polish lap? That should tell you something. Your polish and lap choices depend on the gem material you’re polishing. If you’re dealing mostly with natural gemstones and not using oxide polish, you’re missing out on a faster and easier way to get the job done. Personally, I couldn’t do without my aluminum and cerium oxide polishes. Cerium oxide is a good choice for polishing scapolite. “Scapolite,” 1.45 cts, fancy round brilliant, Tanzania. © Dan Stair Custom Gemstones . Used with permission. This edited version of an article by the late Jeff Graham is part of a special archived informational series from Gram Faceting . Used with permission. Take your love of gemstones To a New Level

Question: What is the craft of cutting and polishing stones or gems?
Answer: Lapidary