[DOC] [TLE] Ruby and Sapphire: Gems of the Mineral Corundum - Geology.com [PAR] The red color is produced by trace amounts of chromium in the mineral. ... Most 
rubies in the market today have been heated to improve their color and clarity. ... 
sapphire, and fancy sapphire: Gem-quality corundum is a highly prized and 
valuable ... Mining small gems from hard rock is possible, but it is very expensive, 
and... [DOC] [TLE] How synthetic ruby is made - material, manufacture, history, used ... [PAR] Chromium gives rubies their characteristic red color, with higher ... Because it 
was so highly prized, the ruby was the first gemstone to be made artificially ... 
During World War II, it was impossible to get rubies from traditional sources ... 
causes a small amount of powder to fall through the fine mesh that forms the 
hopper's floor... [DOC] [TLE] What is corundum and what are its basic qualities? [PAR] Corundum is an aluminum oxide that commonly forms hexagonal ... Red 
corundum is called ruby, blue corundum is called sapphire, and all other colours 
are ... trace amounts of Cr. There is no official cutoff for the amount of Cr needed 
for ruby, but .... Since rubies and sapphires are treasured for their intense colour it 
is no... [DOC] [TLE] Free Flashcards about GEMS & JEWELRY - StudyStack [PAR] THIS HIGHLY PRIZED FORM OF CORUNDUM GETS ITS RED COLOR FROM 
MINUTE AMOUNTS OF CHROMIUM, RUBIES. THE WATERS NORTH OF... [DOC] [TLE] Sapphire, Gemstone of Many Colors - Jewelry Television [PAR] Is it the rich, blue colors of the highly prized Kashmir stones? ... Yet in nature, 
most corundum has some color, due to small amounts of impurities called trace... [DOC] [TLE] ruby | gemstone | Britannica.com [PAR] Gemstone composed of transparent red corundum, a mineral form of ... the 
replacement of a small number of aluminum atoms by chromium atoms (1 in ... 
On exposure to high temperature, ruby becomes green but regains its original 
colour upon ... of forming artificial ruby from purified ammonia alum and small 
amounts of... [DOC] [TLE] Red Ruby | Causes of Color - Webexhibits [PAR] Small quantities of rubies are also found in Sri Lanka, Cambodia, Pakistan, ... is 
known as corundum, and as colorless sapphire when in gem-quality form. ... 
Once one out of every hundred aluminum atoms is replaced by chromium ... is a 
small blue transmission, giving ruby its deep red color with purple (bluish) 
overtones. [DOC] [TLE] Gemstones - Chemistry Encyclopedia - structure, number, atom ... [PAR] Industrial-grade diamonds have even been made synthetically at very high 
pressures and ... Its red color results when chromic ions (Cr 3+ ) replace some of 
the ... Sapphire, like ruby, is made of corundum (Al 2 O 3 ) and has a hardness of 
9. ... Its light blue to blue-green color results from small amounts of iron in the 
crystal. [DOC] [TLE] Ruby: The gemstone Ruby information and pictures [PAR] Detailed gem and jewelry information guide about the corundum red ... Ruby is 
distinguished for its bright red color, being the most famed and fabled red 
gemstone. ... is known as a "Star Ruby", and if transparent can be very highly 
prized. ... The color of Ruby is usually caused by minute inclusions of the metal 
chromium. [DOC] [TLE] SPINEL main - The Department of Geological Sciences [PAR] Red and pink spinel is colored by trace quantities of Cr; blue, violet, orange and 
green ... naturals from synthetics, or synthetic spinel from corundum (see below). 
... R.I.: about 1.72 for most natural gem material; red spinel may be as high as ... 
As with other colored stones, depth and purity of color and clarity are highly 
prized. [DOC] [TLE] Sapphire & Ruby - Lambert Industries [PAR] Rubies and Sapphires Are One of the Most Prized Gems ... For example, a top 
quality, larger size emerald gets top ratings for beauty ... of colors and the color is 
dependent on which type of trace (very small amount) ... If the corundum crystal is 
a color other than

Question: This highly prized form of corundum gets its red color from minute amounts of chromium
Answer: Rubies