Opal
The most desirable play of color in an opal
Red
Cryptocrystalline quartz is also known as
Chalcedony
What color is untreated Tanzinite?
Brownish
What is the most common color of untreated, natural topaz?
Colorless
What is white?
The country that supplies the majority of the world's gem-quality tourmaline
Where is Brazil?
Most rare and valuable spinel hue
What is red?
What can have a dramatic effect on its face-up color?
What is cut?
About 90% of the world's total opal supply comes from this country
Australia
In the nineteenth century, a major source of amethyst was discovered in what country?
Brazil
The most-prized chatoyant gem in the world is
cat's-eye chrysoberyl
What trace element gives Aquamarine its color?
Iron
Very fine texture jadeite
What is Old Mine?
The size of the finest peridot color
What is over 10 carats?
Garnet and spinel are rarely
What is treated?
Most colored stones are sold by
What is weight?
The network of tiny fractures that develops when an opal loses moisture
Crazing
Name the crystal system quartz is apart of
Trigonal
Pleochroic and phenomenal gems must be precisely oriented to ?
display their optical effects properly
Where can you find the only source of Red Beryl?
Utah, Wah Wah Mountains
The three most important qualities of jade
What are color, transparency, and texture?
What are high, low (metamict), and intermediate?
Garnet's crystal habit
What is a dodecahedron?
How most colored stones are mined
What are independent or small-scale miners?
Play-of-color that's seen only when light travels through an opal to the eye is called
Contra Luz
Amethyst is found in the US in the Four Peaks Mine in which state?
Arizona
What contains carbon inclusions that form the imprint of a dark cross, usually against an opaque white/gray/green/reddish/ or light brown background?
Chiastolite
Topaz forms in which crystal system?
orthorhombic
Jadeite's toughness
What is exceptional?
Copper-bearing tourmaline are found in which 2 countries?
Where are Brazil and Mozambique?
Spinel's crystal habit
What is an octahedron?
What kind of cut is demanded for relatively available, moderately priced rough?
What is precise cutting and proportions?
Which treatment involves immersing opal in concentrated sulfuric acid?
Sugaring
""Swiss lapis"" or ""blue onyx"" is a misnomer for
Dyed blue jasper
Andalusite's pleochroism hues are often visible simultaneously through?
The Gem's Crown
The major source of imperial topaz is
Ouro Preto, brazil
The main polishing center for jadeite from around the world
Where is China?
Where most gem tourmalines are formed
What are pegmatites?
This element colored tsavorite into a pure green or green with a slight amount of blue
What is vanadium?
What kind of stones appear more saturated when cut from the same rough?
What are larger stones?
Plastic imitation opal was first marketed in the late 1980's in what country?
Japan
The mica platelets in green aventurine quartz are colored by what element?
Chromium
What is the most convincing tanzanite imitation?
Synthetic forsterite
This recent source is the leading producer of small, commercial-quality aquamarine
China
How Asia describes the extent of jade treatment?
What is Type A, B, and C?
The location of the main suppliers of tourmaline to the Chinese royal court in the late 19th to early 20th century
Where is San Diego County, California?
What causes a stronger red hue in spinel?
What is higher chromium content?
Stones that typically show some eye-visible inclusions that don’t detract from the stone’s overall beauty
What are Type II?
The major sources of fire opal are located in what country?
Mexico
Which of the following aggregates has the smallest crystal size?
Cryptocrystalline
The most-prized chatoyant gem in the world is?
Cats Eye Chrysoberyl
What trace element causes the color in red beryl?
Manganese
The environment in jadeite is formed
What is metamorphic?
Low zircon has how much radiation?
What are high levels of radiation?
The transparent orange to cinnamon-colored variety of the grossular species
What is hessonite?
What is a memo?
Play-of-color is produced by the interaction of _________ with opals internal structure of stacked silica spheres
Light
Chrysoprase means what in Greek?
Golden Apple
Where was tanzanite discovered?
Merelani, Tanzania, Africa
What is beryl's crystal system?
Hexagonal
Trade term for finer green nephrite
What is "Polar Jade"?
Country that supplies the world with most of its large, fine-color peridot
Where is Myanmar?
The substitution of one chemical element for another in the crystal structure of a mineral
What is isomorphous replacement?
A selection of goods loaned by a dealer by another wholesaler or a gem cutter
What is consignment?
What opal commands the highest prices of all opal types?
Black Opal
Before a huge amethyst deposit was found in Brazil in the 19th century, what country was the major source of amethyst?
Russia
Tanavyte is a trade name for?
Purple Synthetic YAG
The finest cyclamen pink topaz is found where?
Pakistan
What does nephrite have that makes it more resistant to fracturing compared to jadeite?
What is interlocking fibrous structure?
Where supplies the world with most of its commercial calibrated peridot?
Where is Arizona?
The most important source of rhodolite since the 1960s
What step in the cutting process has the greatest impact on a finished gem's value?
What is preforming?
Who created the first marketable synthetic opal?
Pierre Gilson
A property of some crystals that causes them to vibrate at a constant frequency when subjected to an electrical current is called what?
piezoelectricity
Where is a major source of cat's-eye chrysoberyl?
Sri Lanka
Gems that are colored by trace elements or defects in its crystal structure rather than by elements of its basic chemistry is called?
Allochromatic
How nephrite is formed
What is metasomatism?
Africa’s most economically important tourmaline sources
Where are Nigeria and Mozambique?
Color-change garnets are usually what mixtures with vanadium as a coloring agent?
What is pyrope-spessartine?
Calibrated gems in a parcel should be within this much of each other
What is 0.10 mm?