Exam (elaborations)
GIA COLORED STONES ASSIGNMENT 19 OPAL QUESTIONS AND ANSWERS
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GIA COLORED STONES ASSIGNMENT 19 OPAL QUESTIONS AND ANSWERS
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Name: Score:44 Multiple choice questions
Definition 1 of 44
thin layers of precious opal, cut to include matrix.
precious opal
white opal
simple opal
boulder opal
Definition 2 of 44
What is semi-black opal's background color?
dark purple
grayish
brown
yellowish
Definition 3 of 44
A gem material's host rock, which sometimes becomes part of the finished gem.
matrix
phenocryst
background
clasts
,Definition 4 of 44
Commercial-quality white opal dominates the _____ ___________.
European market
Asian market
US market
African market
Definition 5 of 44
Opal that lacks play-of-color
fire opal
potch opal
boulder opal
black opal
Definition 6 of 44
Which treatment involves immersing opal in concentrated sulfuric acid?
water
light
carbohydrates
sugar
Definition 7 of 44
What is the transparency range of white opal?
translucent to opaque
background
semitransparent to translucent
matrix
,Definition 8 of 44
Who created the first marketable synthetic opal?
Auguste Verneuil
Carroll Chatham
Pierre Gilson
Contra Luz
Definition 9 of 44
Most opal formed...
15 to 30 million years ago
150 to 300 thousand years ago
15 to 30 thousand years ago
30 to 30 million years ago
Definition 10 of 44
Individual opals can ________ _________ in appearance and quality
change slightly
vary widely
appear identical
remain constant
Definition 11 of 44
Boulder opal is mined only in the state of _______________ in northeastern Australia.
Western Australia
New South Wales
Victoria
Queensland
, Definition 12 of 44
Cutters typically fashion commercial-quality white opal and assembled opal into standard
___________ _________.
custom sizes
large pieces
irregular shapes
calibrated sizes
Definition 13 of 44
Try to keep conditions, methods, and samples consistent when you ____________ opal.
sell
transport
store
evaluate
Definition 14 of 44
The type of matrix found as a layer in finished boulder opal is...
ironstone
rock salt
boulder opal
slocum stone
Definition 15 of 44
What is the transparency of gray-base black opal?
opaque
large
thin
light
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