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Colored Stones-GIA
(part III)
74
Geology
Undergraduate 3
09/27/2011

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Cards

Term
Most colored stones are sold
Definition
by weight
Term
What category of colored stone is often sold per peice?
Definition
small, inexpensive
Term
What category of colored stone is often sold per peice?
Definition
Small, inexpensive
Term
Sieves are most useful for sorting round gems with diameters
Definition
3 mm and below
Term
When you first start to count a large pile of small gems, it's best to separate them into groups of
Definition
5
Term
The color of a sorting pad should be
Definition
neutral
Term
Colored stones with higher values usually have
Definition
medium to medium-dark tone and vivid saturation
Term

If an emerald weighs 3.50 carats and the stone's cost is $10,500.00, what is it's per-carat price?

 

 

(Divide $10,500 by 3.50 cts.)

Definition
$3.000.00
Term

If a parcel of carats weighs 382.00 cts. and the per-carat price is $80.00, what is the total cost of the parcel?

 

(Multiply the parcel's carat weight by the price per carat.)

Definition
$30,560.00
Term

If a parcel of amethysts contains 1,000 stones and weighs a total of 1,542.00 with a cost $0.75 per carat,what is the unit price?

 

(Multiply 1,542.00 cts (parcel total weight) by $0.75 (price per carat) for the parcel price of $1,156.00.  Divide $1,156.00 by 1,000 (total # of stones in the parcel) for the unit price of $1.1565 rounded to $1.16.

Definition
$1.16
Term

What is the cost of a ruby that weighs 5.76 cts.and has a per-carat price of $5,500.00?

 

(Multiply 5.76 cts. by $5,500.00)

Definition
$31,680.00
Term
Which type of rough is usually faceted?
Definition
Highly included
Term
To retain as much weight as possible from rare, high-quality rough, cutters would most likely vary
Definition
proportions
Term
Removing heavly included sections from gemstone rough by carefully tapping it with a small hammer is known as
Definition
cobbing
Term
Rough that's ground to the approximateshape of the finished stone is called
Definition
preform
Term
Which is most likely to undergo cobbing?
Definition
Commericial-quality amethyst rough
Term
Which cutting stage has the greatest impact on the value of the finished gem?
Definition
Preforming
Term
Which colored stone variety has cutting challenges due to the vunerable cleavage planes?
Definition
Tanzanite
Term
Translucent to opaque rough is often cut into a
Definition
Brillant cut
Term
Which is a carved design that projects slightly from a flat or curved serface?
Definition
Cameo
Term
Colored stones cut flat with shallow pavillions usually have areas of lower color intensity called
Definition
windows
Term
A cutter can darken the color of a pale stone by cutting a
Definition
deep pavillion
Term
to judge brilliance, view the stone
Definition
Face up
Term
The purpose of most variations in a colored stone's face up outline is to
Definition
save weight
Term
Excessive bulge on a step cut
Definition
addds weight
Term
Colored stones that rate "fair" for brilliance have
Definition
between 25 and 40 percent brilliance
Term
What is Myammar's most important gem export?
Definition
ruby
Term
Which location produces the majority of rubies that end up in mass-produced jewerly?
Definition
Mong Hsu
Term
Which trade term describes a mixture of gem qualites that represents unsorted production from a particular mine?
Definition
Mine run
Term
Which term describes a specific rough gemstone quality range, usually determined by color, size, clarity and price?
Definition
Grade
Term
Where is rough from Mong Hsu brought into Thailand?
Definition
Mae Sai
Term
In mining terms,the theft of a mine's productiom by it;s workers is known as
Definition
high grading
Term
Which of the following is a quantity of stones, sometimes of similar size and quality, from a single mine or from many different sources?
Definition
Parcel
Term
Which of these is a cutting center for colored stones in Thailand?
Definition
Chantaburi
Term
Materials cut free size are normally
Definition
Large, important stones
Term
Gemstones cut to fit standard mountings are known as
Definition
calibrated sizes
Term
The market sector where better-quality gemstones are used in well-finished, moderately priced jewerly is known as
Definition
middle market
Term
Which term describes a random sample from a parcel of gemstones, often used to asses the parcel's overall quality?
Definition
Cut
Term
Which of the following is a price for buying an entire parcel of gems, or a substantial part of it?
Definition
Lot price
Term
Which of the following is a premium price for selecting stones from a parcel?
Definition
Pick price
Term
Which gemstone occurs in almost every color?
Definition
Tourmaline
Term
The first impression of an object's basic color is it's
Definition
hue
Term
Generally, cool-colred hues with low saturation look
Definition
bluish
Term
Use trade terms that imply geographic orgin only if the
Definition
gem's actual source is known.
Term
Which trade term describes certain tourmalines?
Definition
Paraíba
Term
Which abbreviation does the GIA Colored Stone Grading System use for a slightly purplish red hue?
Definition
slpR
Term
 In practice, what GIA Colored Stone Grading tone levels apply to grading transparent colored stones?
Definition
2 through 8
Term
A see-through area in a transparent gemstone's bodycolor that usually results from the way the gem was cut is called
Definition
a window
Term
A window usually differs from the rest of the stone in
Definition
saturation
Term
Extinction results from
Definition
deep pavillions
Term
The color of the background for grading a colored stone should be
Definition
neutral
Term
What type of lighting is best for grading color in a colored stone?
Definition
Daylight-equivalent flurescent
Term
Higher levels of saturation are usually found in stones with
Definition
dark to very dark tone
Term
What two coloring agents are usually responsible for color change in gemstones?
Definition
Chromium and vanadium
Term
Emission of visable light by a material when exposed to invisible ultraviolet radiation is
Definition
fluorescence
Term
A characteristic or irregularity confined to the surface of a polished gemstone is a
Definition
blemish
Term
An angular, hollow space that resembles a mineral inclusion is called a
Definition
negative crystal
Term
A general term for a break in a stone is
Definition
feather
Term
An inclusion with the most negative effect on a colored stone's clarity would be located
Definition
under the table
Term
In which colored stone clarity type are the gems usually eye-clean?
Definition
Type I
Term
The highest clarity grade for a colored stone is
Definition
eye-clean
Term
The term "silk" describes
Definition
a group of fine, needle-like inclusions
Term
Fingerprints are
Definition
Partially healed fracture planes
Term
Fingerprints are
Definition
Partially healed fracture planes
Term
Which of these gems are classified as a Type III?
Definition
Emerald
Term
In which of the following colored stone clarity grades do the definitions vary for each clarity type?
Definition
Moderately included
Term
Which of these clarity characteristics would usually have the greatest impact on a gem's marketabiltiy?
Definition
A large, unhealed feather
Term
Gems that are usually eye-clean include:
Definition
spodumene, yellow beryl and aquamarine
Term
Inclusions are important to gemologists because they
Definition
Can help separate natural from synthetic gems
Term
Growth zoning in a colored stone is evidence of
Definition
crystal growth
Term
Two factors that determine an inclusion's impact on a gem's value are
Definition
position and relief
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