GIA Colored Stones Exam 101-150 Flashcards
Bluish_green to green.
Finest Emerald
What element increases the amount of blue in an emerald’s color?
Iron
The trade term “Zambian” describes emeralds with ________________ and ______________ than Columbian.
More bluish color and darker tone
What type source rock are Brazilian emeralds mined from?
Pegmatites; where they intersect with schists.
To emphasize the most desirable color; cutters orient a fashioned emerald with it’s table _____________ .
Perpendicular to the crystal length
What is the estimated percentage of fashioned emeralds that contain filled fractures?
90% or more
What to countries account for about 75% of emerald purchases worldwide?
US and Japan
Four major emerald sources are Columbia; Zambia; Brazil and _____________ .
Zimbabwe
One of Columbia’s traditional emerald mines is called ____________ .
Coscuez
Compared to emerald’s from other sources; emeralds from African mines generally contain ____________ .
Fewer fractures.
Emerald is a variety of what species?
Beryl
What coloring of the stone disqualifies it from being considered and emerald.
Too yellowish or too bluish
Name the two most common clarity characteristics in an emerald.
Fractures and liquid inclusions
What does the trade term “jardin” mean?
jardin _ French word for garden. A descriptive term for an emerald’s inclusions that look mossy or garden_like.
Natural emerald with colorless or colored filling.
Level 1 Treatment
Natural emerald having filling that is minor; moderate or significant.
Level 2 Treatment
Type of filler (upon request) if the laboratory is equipped.
Type 3
Does the GIA provide Level 3 emerald treatment identification?
No.
What is the name for an emerald in which it’s inclusions form a star_like pattern of rays.
Trapiche
What are the three signs that point to an “emerald” being a glass immitation?
Gas bubbles; Concave Surfaces; Rounded facet junctions
Reddish orange to orange red.
Imperial topaz
The most valuable topaz varieties are _____________ .
Pink; Red
Most gem_quality topaz comes from what growth source?
Pegmatites.
The term precious topaz is used for ___________ .
Yellow to orange stones.
What is the most common color of untreated; natural topaz?
Colorless.
Wah Wah mountain area.
Imperial topaz source
In order to obtain a treated pink color; yellow to reddish brown topaz must contain elemant
Chromium
Medium dark blue to slightly greenish blue.
Finest Aquamarine
Which method is used to produce synthetic aquamarine?
Hydrothermal
The most important source country for aquamarine is ____________ .
Brazil
Which recent source is the leading producer of small; commercial_quality aquamarine?
China
Most aquamarine has it’s color improved by what treatment?
Heat
What color is morganite beryl?
Pink
What gemstone is the rarest beryl?
Red beryl
What color is morganite beryl?
pink
The only source of red beryl is located in what US state?
Utah
What causes the wide variety of colors in topaz?
Color centers and chromium.
Why does topaz require special care and handling?
Cleavage.
What area in Brazil is the world’s major commercial source of imperial and red topaz.
Ouro Preto
Which treatments are involved with topaz?
Heating and irradiation
What are the two most important considerations for buyers of treated blue topaz?
Price and uniformity
The finest most saturated color of aquamarine is normally shown in ____________ .
Large sizes.
What three countries are the leading producers of aquamarine?
Brazil; Pakistan; China
What trace element causes red beryls color?
Manganese
What distinguishes green beryl from emerald?
Tone and saturation
Because of topaz’s elongation; how are they cut?
long ovals; pears; emerald
What is the trade term for a highly prized; vivid blue adularescence displayed for the finest moonstone?
Blue sheen
Tiny tension cracks in moonstone that iterfere with adularescence and reduce value are called _______ .
Centipedes
What is the trade term for an imitation of aventurine feldspar made of glass that contains copper crystals?
Goldstone
Why does feldspar; spodumene and diopside have weak consumer recognition?
Because of unpredictable supplies
