GIA Colored Stones Exam 1-50 Flashcards
Velvety blue to violetish blue; in medium to medium_dark tones; with strong to vivid saturation.
fine sapphire
What trace elements cause the blue of sapphire?
iron and titanium
A smoky corundum that turns blue when treated is called _______ .
Dhun
True or False: Higher levels of iron make basalt_hosted sapphires darker than non_basaltic sapphires.
TRUE
What is the trade name considered as the finest blue sapphire?
Kashmir
Is color zoning a common sapphire characteristic?
Yes
True or False: Most sapphires are heat treated to improve their appearance.
TRUE
True or False: Fine quality; untreated sapphires make up a small but extremely valuable segment of the sapphire market.
TRUE
What country buys about half of the blue sapphires on the world market?
USA
Kashmir sapphires owe their reputation to a brief period of output during what time period?
1880’s
What country is a major center of the corundum trade; funneling a steady flow of gems from worldwide sources into the consumer market?
Thailand
What country is the world’s largest source of dark blue; commercial quality blue sapphires?
Australia
What country has become a significant source of good to fine quality blue sapphires?
Madagascar
What is the most common sapphire synthesis method?
Flame fusion
A milky; grayish; or brownish corundum that can be treated to a fine blue color is called ________ .
Geuda
Blue to violetish blue.
Fine blue sapphire
What trace elements cause blue sapphire’s color?
titanium and iron.
Blue sapphires that originate in basaltic rock generally have a _________ .
higher iron content.
Finer quality Kashmir blue sapphires typically show what type of appearance?
Velvety
Type of sapphire described as inky.
Australia
Blue sapphire’s most common crystal habit is _________.
spindle_shaped hexagonal pyramid or bipyramid.
Most fine sapphires of 100 cts. come from what country?
Sri Lanka
What country emerged in the 1990’s as a significant source of good to fine quality sapphire?
Madagascar
What country is the world’s largest blue sapphire EXPORTER ?
Thailand
The sapphire market level supplied by Switzerland is ________ .
upper.
Kashmir’s most important sapphire production period was from ________ to ________ .
1881 to 1887.
When did Madagascar become a significant source of blue sapphire?
1990’s
What location supplies sapphires that are most likely not heat_treated?
Yogo Gulch
A “Kashmir” sapphire’s blue is also known as _______ .
Cornflower blue.
A “Burmese” sapphire’s blue is known as ______ blue and is considered somewhat _______ .
Royal ; inky
The “Ceylon” or “Sri Lanka” sapphire’s saturation is _______ and ________ . The tone is _________ to _________ .
grayish and strong saturation; light to medium light tone
The “Palin” or “Cambodian” sapphires are typically ______ to _______ in color and look best when fashioned into smaller sizes.
violetish blue to slightly greenish blue
The “Kanchanaburi” sapphires are less saturated and are generally _______ to _______ in color with a ______ to _________ tone. Minute inclusions cause it to have a grayish appearance.
blue to greenish blue color; light to dark tone; similar to Sri Lankan but; not as brilliant
Thai sapphires are ________ to _________ in color and often described as _________ or _________ .
violetish blue to slightly greenish blue; inky blue or blue_black
Australian sapphires often show _____________ plechroism.
strong greenish blue
Lapis Lazuli is valued for its ___________ and rich ________ color.
history ; blue
What produces lapis lazuli’s prized royal blue color?
lazurite
Lapis Lazuli’s value is based on color and the presence or absence of _________ or _________ .
calcite or pyrite
What 3 treatments are used with lapis?
dyed; impregnated with wax or plastic; heated and then dyed
What country is the major source for lapis lazuli?
Afghanistan
What materials have been used as lapis immitations?
Glass; plastic and ceramic
People value turquoise for it’s combination of what two traits?
ancient heritage and attractive color
Turquoise is judged by what three factors?
color; texture; matrix
What is the most prized color of turquoise?
intense / uniform /medium blue
What element causes turquoise to appear greenish blue?
Iron
What element causes turquoise to have a pure blue color?
Copper
What location is the world’s largest producer of turquoise?
Southwestern US
What country is the major source for top color turquoise?
China (Hubai Province)
What is the most common turquoise immitation?
Plastic
The finest grade of lapis lazuli is called ________ .
Afghan
