GIA Colored Stones Exam 551-600 Flashcards
The color of a sorting pad should be ___________ .
neutral
Colored stones with higher value usually have what color characteristics?
medium to medium_dark tone and vivid saturation
Amber is actually _____________ .
hardened tree resin
Immature amber is known as _____________ .
copal
What is the most valuable amber color?
red
What type of coral is a calcium carbonate?
pink
What is coral’s most valuable color?
red
What are the two conchiolin coral colors?
black and golden
What treatment can create a golden color from black coral?
bleaching
What organic shows a structure called “engine turning” which looks like lines created on a lathe?
ivory
What animal’s tusk produces the most valuable ivory?
elephant
Paua is a Maori name for __________ .
albalone shell
Tortise shell is composed of what?
protein
Jet is an ornamental form of ___________ .
lignite coal
What country is the major source for jet?
England
Name a natural glass gem.
moldavite
Where is the only source of benitoite located?
California
What are the circular marks sometimes left in amber when treaters heat and oil it?
sun spangles
How old does tree resin have to be before it is called amber?
1 million years old
Nearly all trade in new elephant ivory has been illegal since what time period?
mid 1970’s
What is the most difficult shape to produce in pearl culturing?
round
What is the name of the largest gem_quality natural pearl?
Dudley
Pearl colors are usually _________ .
low in saturation
In the trade; Tahitian cultured perals witha dark green_gray to blue_gray bodycolor and rose’ to purple overtones are called ____________.
peacock
What overtone color increases the value of akoya cultured pearl with white bodycolor?
rose’
When mollusks live in cooler water; they form pearls with ___________ .
thicker nacre
Pearls that show noticeable surface characteristics are considered ____________ blemished.
severely
The best way to clean pearls is with ____________ .
warm; mild soapy water
The nacre quality classification described as “Nucleus not noticeable; no chalky appearance” is classified as __________ .
acceptable
The matching level that describes a group of pearls that have minor variations in uniformity is considered ____________ .
good
Farmers of every cultured pearl type does this after harvest.
wash; dry; sort
Almost all akoya and Chinese freshwater pearls are __________.
bleached
Usually; the diameters of the cultured pearls in a hank vary from each other by nor more than how many millimeters?
0.5mm
Essence d’orient is a mixture of ___________.
fish scales and varnish
What happens when saltwater cultured pearls are exposed to gamma rays?
the bead nucleus darkens
All pearls display bodycolor; and some also have what characteristics?
overtone; orient; both
A pearl with one or more grooved ridged rings all the way around it is called a ___________.
circled pearl
A mixture of clear varnish and fish scales used in making imitation pearls is called _________ .
essence d’orient
A cultured pearl with a hole drilled all the way through; sometimes called drilled_through is called ___________.
full_drilled
A cultured pearl with a hole drilled halfway through to permit mounting on a post is called ______________.
half drilled
A procedure that includes cleaning buffing and sometimes bleaching; done to make cultured pearls presentable and appealing is called ___________.
process
Blemishes or irregularities confined to a pearl’s surface is called a ________ .
surface characteristic
A cultured pearl with any unsightly potion cut or ground off is called a ____________.
three_quarter_cut
Features used to judge the quality and value of pearls are called __________.
value factors
Most gemstones form in the __________.
continental crust
Rocks altered by heat and pressure are ___________.
metamorphic
What gem can crystallize in volcanic rock from gasses released by magma?
Vietnamese ruby
Where is the key locality for hydrothermal gems?
Ouro Preto; Brazil
What gems form by metamorphism?
ruby; emerald; alexandrtie; tanzanite; tsavorite
Heat and pressure transform limestone into ___________.
marble
