Fineness - wikipedia Fineness The fineness of a precious metal object ( coin, bar, jewelry, etc. ) represents the weight of fine metal therein, in proportion to the total weight which includes alloying base metals and any impurities. Alloy metals are added to increase hardness and durability of coins and jewelry, alter colors, decrease the cost per weight, or avoid the cost of high - purity refinement. For example, copper is added to the precious metal silver to make a more durable alloy for use in coins, housewares and jewelry. Coin silver, which was used for making silver coins in the past, contains 90 % silver and 10 % copper, by mass. Sterling silver contains 92.5 % silver and 7.5 %, by mass, of other metals, usually copper. Various ways of expressing fineness have been used and two remain in common use : millesimal fineness expressed in units of parts per 1,000 and karats used only for gold. Karats measure the parts per 24, so that 18 karat = ⁄ = 75 % and 24 karat gold is considered 100 % gold. Contents 1 Millesimal fineness 1.1 Platinum 1.2 Gold 1.3 Silver 2 Karat 2.1 Measure 2.2 Volume 2.3 Etymology 3 Verifying Fineness 4 Fine weight 5 Troy mass of silver content 6 See also 7 References 8 External links Millesimal fineness Millesimal fineness is a system of denoting the purity of platinum, gold and silver alloys by parts per thousand of pure metal by mass in the alloy. For example, an alloy containing 75 % gold is denoted as `` 750 ''. Many European countries use decimal hallmark stamps ( i.e. ' 585 ', ' 750 ', etc. ) rather than ' 14K ', ' 18K ', etc., which is used in the United Kingdom and United States. It is an extension of the older karat system of denoting the purity of gold by fractions of 24, such as `` 18 karat '' for an alloy with 75 % ( 18 parts per 24 ) pure gold by mass. The millesimal fineness is usually rounded to a three figure number, particularly where used as a hallmark, and the fineness may vary slightly from the traditional versions of purity. Here are the most common millesimal finenesses used for precious metals and the most common terms associated with them. Platinum 999.5 : what most dealers would buy as if 100 % pure ; the most common purity for platinum bullion coins and bars 999 -- three nines fine 950 : the most common purity for platinum jewelry 925 900 -- one nine fine 850 750 Gold 1 troy ounce of four nines fine gold ( 999.9 ) 999.999 -- six nines fine : the purest gold ever produced. Refined by the Perth Mint in 1957. 999.99 -- five nines fine : the purest type of gold currently produced ; the Royal Canadian Mint regularly produces commemorative coins in this fineness, including the world 's largest at 100 kg. 999.9 -- four nines fine : e.g., ordinary Canadian Gold Maple Leaf and American Buffalo coins 999 -- 24 karat, also occasionally known as three nines fine : e.g., Chinese Gold Panda coins 995 : the minimum allowed in Good Delivery gold bars 990 -- two nines fine 986 -- Ducat fineness : formerly used by Venetian and Holy Roman Empire mints ; still in use in Austria and Hungary 958.3 -- 23 karat 916 -- 22 karat : historically the most widely used fineness for gold bullion coins ; currently used for British Sovereigns, South African Krugerrands and American Gold Eagles 900 -- one nine fine : mostly used in Latin Monetary Union mintage ( e.g. French and Swiss `` Napoleon coin '' 20 francs ) 834 -- 20 karat 750 -- 18 karat 625 -- 15 karat 585 -- 14 karat 417 -- 10 karat 376 -- 9 karat 333 -- 8 karat : minimum standard for gold in Germany after 1884 Silver 999.99 -- five nines fine : The purest silver ever produced. This was achieved by the Royal Silver Company of Bolivia. 999.9 -- four nines fine : ultra-fine silver used by the Royal Canadian Mint for their Silver Maple Leaf and other silver coins 999 -- fine silver or three nines fine : used in Good Delivery bullion bars and most current silver bullion coins 980 : common standard used in Mexico ca. 1930 -- 45 958 -- Britannia silver 950 -- French 1st Standard 925 -- Sterling silver 917 : a standard used for the minting of Indian silver ( rupees ), during the British raj 916.66 -- ⁄ : the standard established by Maryland state law in 1814 for all silver sold in Baltimore. Last used in 1843. 900 -- one nine fine or 90 % silver : e.g., all 1792 -- 1964 U.S. silver coins 835 : a standard predominantly used in Germany after 1884, and for the minting of coins in countries of the Latin Monetary Union 833 : a common standard for continental silver especially among the Dutch, Swedish, and Germans 830 : a common standard used in older Scandinavian silver 800 : the minimum standard for silver in Germany after 1884 ; Egyptian silver ; Canadian silver circulating coinage from 1920 - 1966 / 7 750 : an uncommon silver standard found in older German, Swiss and Austro - Hungarian silver 720 : e.g., many Mexican and Dutch silver coins 500 : Standard used for making British coinage after 1920 Karat The karat ( not carat as a unit of mass ; symbol : K or kt ; US ) or carat ( symbol : C ) is a fractional measure of purity for gold alloys, in parts fine per 24 parts whole. The karat system is a standard adopted by US federal law. Measure K is the karat rating of the material, M is the mass of pure gold in the alloy, and M is the total mass of the material. Therefore, 24 - karat gold is pure ( while 100 % purity is unattainable, this designation is permitted in commerce for 99.95 % purity ), 18 - karat gold is 18 parts gold, 6 parts another metal ( forming an alloy with 75 % gold ), 12 - karat gold is 12 parts gold ( 12 parts another metal ), and so forth. In England, the karat was divisible into four grains, and the grain was divisible into four quarts. For example, a gold alloy of ⁄ fineness ( that is, 99.2 % purity ) could have been described as being 23 - karat, 3 - grain, 1 - quart gold. The karat fractional system is increasingly being complemented or superseded by the millesimal system, described above. Conversion between percentage of pure gold and karats : 58.33 -- 62.50 % = 14K ( acclaimed 58.33 % ) 75.00 -- 79.16 % = 18K ( acclaimed 75.00 % ) 91.66 -- 95.83 % = 22K ( acclaimed 91.66 % ) 95.83 -- 99.95 % = 23K ( acclaimed 95.83 % ) 99.95 -- 100 % = 24K ( acclaimed 99.99 % ) Volume However, this system of calculation gives only the mass of pure gold contained in an alloy. The term 18 - karat gold means that the alloy 's mass consists of 75 % of gold and 25 % of alloy ( s ). The quantity of gold by volume in a less - than - 24 - karat gold alloy differs according to the alloy ( s ) used. For example, knowing that standard 18 - karat yellow gold consists of 75 % gold, 12.5 % silver and the remaining 12.5 % of copper ( all by mass ), the volume of pure gold in this alloy will be 60 % since gold is much denser than the other metals used : 19.32 g / cm for gold, 10.49 g / cm for silver and 8.96 g / cm for copper. This formula gives the amount of gold in cubic centimeters or in milliliters in an alloy : V Au = M a × k t 24 19.32 ( displaystyle V_ ( \text ( Au ) ) = ( \frac ( M_ ( \text ( a ) ) \times ( \frac ( kt ) ( 24 ) ) ) ( 19.32 ) ) ) where V is the volume of gold in cubic centimeters or in milliliters, M is the total mass of the alloy in grams, and kt is the karat purity of the alloy. To have the percentage of the volume of gold in an alloy, divide the volume of gold in cubic centimetres or in millilitres by the total volume of the alloy in cubic centimetres or in millilitres. For 10 - carat gold, the gold volume in the alloy represents about 26 % of the total volume for standard yellow gold. Talking about purity according to mass could lead to some misunderstandings ; for many people, purity means volume. Etymology Karat is a variant of carat. First attested in English in the mid-15th century, the word carat came from Middle French carat, from Italian carato, both which came from Greek kerátion ( κεράτιον ) meaning carob seed ( literally `` small horn '' ) ( diminutive of κέρας -- keras, `` horn '' ), also from Arabic qīrāṭ meaning `` fruit of the carob tree '', also `` weight of 4 grains '', ( قيراط ) and was a unit of mass though it was probably not used to measure gold in classical times. In 309 CE, Roman Emperor Constantine I began to mint a new gold coin solidus that was ⁄ of a libra ( Roman pound ) of gold equal to a mass of 24 siliquae, where each siliqua ( or carat ) was ⁄ of a libra. This is believed to be the origin of the value of the karat. Verifying fineness While there are many methods of detecting fake precious metals, there are realistically only two options available for verifying the marked fineness of metal as being reasonably accurate : assaying the metal ( which requires destroying it ), or using X-ray fluorescence ( XRF ). XRF will only measure the outermost portion of the piece of metal, so it may get fooled by thick plating. This becomes a concern because it would be possible for an unscrupulous refiner to produce precious metals bars that are slightly less pure than what they mark the bar. A refiner doing $1 billion of business each year that marked. 980 pure bars as. 999 fine would make about an extra $20 million in profit. In the United States, the actual purity of gold articles must be no less than. 003 less than the marked purity ( e.g.. 996 fine for gold marked. 999 fine ), and the actual purity of silver articles must be no less than. 004 less than the marked purity. Fine weight A piece of alloy metal containing a precious metal may also have the weight of its precious component referred to as its fine weight. For example, 1 troy ounce of 18 karat gold ( which is 75 % gold ) may be said to have a fine weight of 0.75 troy ounces. Troy mass of silver content Fineness of silver in Britain was traditionally expressed as the mass of silver expressed in troy ounces and pennyweights ( ⁄ troy ounce ), in one troy pound ( 12 troy ounces ) of the resulting alloy. Britannia silver has a fineness of 11 troy ounces, 10 pennyweights, or about 95.83 % silver, whereas sterling silver has a fineness of 11 troy ounces, 2 pennyweights, or about 92.5 % silver. See also Colored gold Electrum Gold as an investment Gold coin Platinum coin Silver as an investment Silver coin Tumbaga References Jump up ^ London Bullion Market Association. `` Definitions ''. Jump up ^ Seyd, Ernest ( 1868 ). Bullion and foreign exchanges theoretically and practically considered. E. Wilson. p. 146. Retrieved 21 March 2012. Jump up ^ `` The Perth Mint : : History ''. Gold Corporation. Retrieved 2011 - 05 - 08. Jump up ^ Thomas, Athol. 90 Golden Years, The story of the Perth Mint. Gold Corporation. p. 58. Jump up ^ Royal Canadian Mint. `` The Million Dollar Coin -- a true milestone in minting ''. Retrieved 13 July 2017. In October 2007, the Million Dollar Coin was certified by Guinness World Records to be the world 's largest gold coin. Jump up ^ `` Fineness of Gold ''. Gold Rate for Today. Archived from the original on August 7, 2013. Retrieved 2013 - 08 - 15. Jump up ^ ``... : : Royal Silver Company : :... ''. Jump up ^ http://www.coinflation.com/canada/ Jump up ^ Melaragno, Michele. The VNR Dictionary of Engineering Units and Measures. Van Nostrand Reinhold. p. 114. Jump up ^ The VNR OXFORD Dictionary for Scientific Writers and Editors. Oxford University Press. p. 56. Jump up ^ `` United States Code, 16 CFR 23.4 - Misrepresentation as to gold content. ''. Jump up ^ Comprehensive Jewelry Precious Metals Overview International Gem Society ( IGS ), Retrieved 01 - 16 - 2015 ^ Jump up to : Harper, Douglas. `` carat ''. Online Etymology Dictionary. Jump up ^ κεράτιον, Henry George Liddell, Robert Scott, A Greek - English Lexicon, on Perseus Jump up ^ Walter W. Skeat ( 1888 ), An Etymological Dictionary of the English Language Jump up ^ κέρας, Henry George Liddell, Robert Scott, A Greek - English Lexicon, on Perseus Jump up ^ carat, Oxford Dictionaries Jump up ^ Vagi, David L. ( 1999 ). Coinage and History of the Roman Empire. II : Coinage. Chicago : Fitzroy Dearborn. p. 100. ISBN 1 - 57958 - 316 - 4. Retrieved 18 November 2011. Jump up ^ Grierson, Philip ( 1968 ). Catalogue of the Byzantine Coins in the Dumbarton Oaks Collection and in the Whittemore Collection. 2 : pt. 1. Washington, DC : Dumbarton Oaks. p. 8. ISBN 0 - 88402 - 024 - X. Retrieved 18 November 2011. Jump up ^ Turnbull, L.A. ; Santamaria, L. ; Martorell, T. ; Rallo, J. ; Hector, A. ( 2006 ). `` Seed size variability : From carob to carats ''. Biology Letters. 2 ( 3 ) : 397 -- 400. PMC 1686184. PMID 17148413. doi : 10.1098 / rsbl. 2006.0476. Jump up ^ `` '' 15 U.S. Code Chapter 8 - FALSELY STAMPED GOLD OR SILVER OR GOODS MANUFACTURED THEREFROM `` ''. External links `` Did carob seeds allow shady diamond deals ? '', New Scientist, Issue 2550 ( 9 May 2006 ), p. 20 ( subscription required ) Retrieved from `` https://en.wikipedia.org/w/index.php?title=Fineness&oldid=800563699 '' Categories : Metallurgy Gold investments Precious metals Units of purity Jewellery making Hidden categories : Articles containing Middle French - language text Articles containing Italian - language text Articles containing Greek - language text Articles containing Arabic - language text Pages containing links to subscription - only content Talk Contents About Wikipedia Čeština Dansk Deutsch Español Français Italiano ಕನ್ನಡ Lietuvių Norsk Norsk nynorsk Oʻzbekcha / ўзбекча Polski Română Русский Slovenčina Українська Edit links This page was last edited on 14 September 2017, at 09 : 26. Text is available under the Creative Commons Attribution - ShareAlike License ; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy. 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Question: the ratio of pure gold in 24 carat gold is
Answer: 100% gold