CS21
The most-prized chatoyant gem in the world is
Cats eye chrysoberyl
When Alexandrite was discovered
1830
When was tanzanite first discovered?
1967
When did TanzaniteOne buy AFGEM and its assets?
2004
Tanzanite ranks what on the Mohs scale?
6 to 7
Iolite and andalusite rank what on the Mohs scale?
7 to 7.5
Alexandrite ranks what on the Mohs scale?
8.5
About what percent of tanzanite is heat treated?
95
What stone is the finest color change gem and the standard for which all other color change gems are judged
Alexandrite
Which gem was named after a Russian czar?
Alexandrite
In iolite, the most valuable main face-up color is
Blue
What color is top-quality alexandrite in daylight?
Blueish green
Cutting tanzanite to emphasize which color usually wastes less of the rough?
Bluish Purple
Untreated tanzanite is typically
Brownish
The color change in alexandrite is caused by
Chromium
What was the old Victorian name for yellow Chrysoberl?
Chrysolite
What are the pleochroic colors for violet iolite?
Light violet, dark violet, and yellow-brown
What are the pleochroic colors for bluish iolite?
Colorless to yellow, blue-gray, and dark violet
What is an old Greek word for cat's-eye chrysoberyl that means ""wavelike form""?
Cymophane
When was alexandrite found in Brazil?
Early 1980s
What makes chrysoberyl the most prized chatoyant gem?
Excellent hardness and durability combined with the sharpest cats eye
What are the pleochroic colors of alexandrite?
Green, orange, and purple-red
Almost all tanzanite is
Heat Treated
What changes during alexandrite's color-change effect?
Hue
What is the trade name for gem quality cordierite?
Iolite
What causes iolite's violetish blue to violet color?
Iron
Where was tanzanite discovered?
Merelani
What is a major source of Iolite, cat's-eye chrysoberyl, and alexandrite?
Sri Lanka
What is the most convincing tanzanite imitation to date?
Synthetic forsterite
Which of the following gems is the most economically important?
Tanzanite
A translucent to opaque pink zoisite, often streaked or mottled with gray or white, is called
Thulite
The name tanzanite was given to transparent blue zoisite by
Tiffany and co
Top-color iolite is
Untreated
Where was alexandrite first discovered?
Ural Mountains in Russia
""Mint chrysoberly"" is colored by
Vanadium
What causes the Cat's eye in chrysoberyl?
light reflecting from needle like inclusions in the gemstones
Tanavyte is a trade name for
purple synthetic YAG
Tanzanite's best color is
strongly saturated blue or violetish blue
