| 347K FINAL EXAM
Answer the following questions as directed. For multiple choice questions
choose the single best answer. There are no "trick questions"; all questions
and answers come from online gem notes, handouts or lecture notes and are
intended to be straightforward. Do not read more into a question than is
asked.
1) Most of the world present production of opal is from
a) Australia
b) Sri Lanka
c) Columbia
d) a and b
e) none of the above
2) The most valuable play-of-color in opal is that which shows
a) a pinfire pattern, with lots of blue
b) a mosaic pattern, with lots of yellow
c) an abundance of red and violet
d) an abundance of green and blue
e) a "flash" or "flame" pattern
3) Opal doublets or triplets are
a) synthetic gems, not natural opal
b) made of natural opal, attached to a cover and/or base.
c) sold by weight, like all other opal
d) not made from natural opal
e) none of the above
4) Synthetic opal can be distinguished from natural opal by
a) refractive index
b) specific gravity
c) u.v. fluorescence
d) microscopic characteristics
e) all of the above
5) Cherry opal is
a) faceted
b) noted for outstanding play-of-color
c) a variety of white opal
d) usually synthetic
e) mined in Australia
6) The term "white opal" refers to all opals that
a) come from a particular location
b) have a distinctive play-of-color
c) have no play-of-color
d) do not show a vivid play-of-color
e) none of the above
7) Citrine is
a) yellow topaz
b) purple quartz
c) usually produced by heating amethyst
d) a variety of microcrystalline quartz
e) none of the above
8) Amethyst is
a) yellow quartz
b) purple sapphire
c) usually produced by heating citrine
d) a variety of coarsely crystalline quartz
e) none of the above
9) Quartz has a refractive index that is
a) low with respect to most faceted gem materials
b) high with respect to most faceted gem materials
c) in the middle of the range of R.I.'s for common colored stones
d) due to trace amounts Fe
e) about the same as garnet
10) Agate and petrified wood are varieties of
a) chalcedony
b) milky quartz
c) chrysoprase
d) carnelian
e) onyx
11) Fibrous microcrystalline quartz varieties include
a) agate
b) onyx
c) sard
d) carnelian
e) all of the above
12) Most gem quartz varieties come from
a) igneous rocks
b) metamorphic rocks
c) gem gravels
d) Africa
e) the U.S.
13) Synthetic amethyst is
a) not very common
b) easy to distinguish from natural amethyst
c) difficult to distinguish from natural amethyst
d) not as dark in color as natural amethyst
e) made of glass
14) Emerald and Aquamarine are names given to
a) green and blue varieties of tourmaline
b) two different minerals, each very different chemically
c) color varieties of the mineral beryl
d) two different idiochromatic minerals that have Fe chromophores.
e) none of the above.
15) The R.I. of emerald
a) is too high to measure with a refractometer
b) is high compared to other colored stones
c) is a principle reason why emeralds are valuable gems
d) is nearly the same as the R.I. of aquamarine
e) is about the same as that of garnet
16) Clarity in emeralds
a) is usually better than in most other colored stones
b) is commonly improved by oiling
c) is not important
d) is more important than color
e) none of the above
17) The most historically important source of emerald is
a) Sri Lanka
b) Brazil
c) Colombia
d) Myanmar (Burma)
e) none of the above
18) Synthetic emeralds made by flux growth are
a) difficult for a gemologist to distinguish from natural emerald
b) easily distinguished from natural emerald by R.I. and
S.G.
c) not presently being manufactured
d) among the least expensive of synthetic gems
e) none of the above
19) Imitation emeralds, made of green glass, can always be identified by
a) RI and SG
b)
polariscope
c) microscope
d) b and c
e) all of the above
20) A recent, significant source of emeralds is
a) Zaire
b) Kenya
c) Australia
d) Zambia
e) Tanzania
21) Aquamarine is commonly
a) oiled to improve clarity
b) heated to improve color
c) irradiated to improve color
d) dyed
e) all of the above
22) Most of the worlds aquamarine comes from
a) Brazil
b) U.S.
c) Sri Lanka
d) Thailand
e) Columbia
23) Gem aquamarine is exclusively a
a) volcanic mineral
b) metamorphic mineral
c) pegmatite mineral
d) low temperature hydrothermal mineral, in veins
e) none of the above
24) Morganite and Heliodor are names given to
a) blue and yellow beryl
b) pink and black beryl
c) pink and purple beryl
d) varieties of tourmaline
e) none of the above
25) Ruby and sapphire are gems names for the mineral
a) corundum
b) beryl
c) garnet
d) topaz
e) none of the above
26) Most ruby and sapphire are mined from
a) pegmatites
b) calcite veins
c) gem gravels
d) kimberlite
e) limestones
27) The worlds finest rubies have historically been associated with mines
in
a) Australia
b) Thailand
c) Sri Lanka
d) Myanmar (Burma)
e) E. Africa
28) "Thai Ruby" is a name that is applied to ruby that
a) comes from Thailand
b) is the finest red color
c) is of inferior color, being dark and/or having a brownish cast
d) has been heat treated
e) has a "pigeon blood" red color
29) The only definitive test for distinguishing synthetic from natural
ruby is
a) examination of inclusions with a microscope
b) u.v. fluorescence
c) R.I. in combination with S.G.
d) hardness
e) birefringence
30) U.V. fluorescence of ruby can be a guide to distinguishing synthetic
from natural ruby because
a) most synthetic rubies don't fluoresce as strongly as naturals
b) most synthetic rubies fluoresce a different color than naturals
c) most natural rubies don't fluoresce as strongly as most synthetics
d) most natural ruby will not fluoresce, but synthetic ruby will.
e) heat treated rubies will not fluoresce
31) Heat treatment of ruby
a) is used to improve clarity
b) is used to improve color
c) can be detected with the aid of a microscope
d) is a widespread practice
e) all of the above
32) Sri Lanka produces ruby that are
a) typically darker in tone than those of Thailand
b) more fluorescent than those of Australia
c) lighter in tone than ruby from other sources
d) only commercially viable after heat treatment
e) also know as Mong Hsu
33) The most highly prized of all sapphire colors is
a) blue sapphire from Kashmir, India
b) pink sapphire from Sri Lanka
c) padparadscha sapphire, from any source
d) violet-blue sapphire from Montana
e) none of the above
34) The most obvious difference between commercial-grade blue sapphire
and top-grade blue sapphire is
a) poorer clarity
b) darker color and poorer transparency
c) much poorer cut
d) overtones of yellow or gray, giving a paler blue
e) smaller size
35) Heat treatment of blue sapphire is
a) a widespread practice
b) used to improve clarity
c) used to lighten color
d) can be detected in most cases with the aid of a microscope
e) all of the above
36) Padparadscha sapphire is
a) a variety of yellow sapphire
b) less valuable than pink sapphire
c) pinkish-orange sapphire
d) not sapphire at all, but a variety of spinel
e) none of the above
37) "Diffusion-treated" blue sapphire is sapphire that has been
a) chemically treated and heated to darken the color near the surface of
the gem
b) irradiated in a special process to lighten the color
c) treated to render the color darker in diffuse light
d) dyed with a blue dye to darken the color
e) heated to improve clarity
38) Synthetic star sapphire cabochons
a) are not commercially available
b) are not really sapphire
c) have been commercially available for more than
40 years
d) are typically more gray-blue than natural star sapphire
e) are "bulkier" or thicker than most naturals.
39) Volcanic glass is known as
a) ametrine
b) moldavite
c) obsidian
d) hyalite
e) carnelian
40) Moldavite is
a) a green glass formed by meteorite impact
b) a form of cryptocrystalline quartz
c) found only in meteorites
d) a diamond immitation
e) none of the above
41) Deep diffusion is a process used to
a) improve clarity in emerald
b) change the color of emerald
c) change the color of sapphire
d) convert opal to quartz
e) all of the above
42) The chromophore in emerald and ruby
a) not known
b) color centers
c) different; one has Fe the other Mn
d) is part of each minerals chemical formula
e) the same
43) All the following places have, or once had, ruby mines except
a) Burma
b) South Africa
c) Sri Lanka
d) Thailand
e) Viet Nam
44) Fancy cut diamonds are those with shapes that are not
a) square cut
b) princess cut.
c) standard round brilliant
d) oval cut
e) heart cut
45) Lasering as an enhancement process is used to improve the appearance of
a) quartz
b) emerald
c) morganite
d) diamond
e) a and d
46) Alluvial (placer) gem deposits are those in which the gems are mined
from
a) hard rocks
b) gravel and/or sand
c) caves
d) pegmatites
e) ancient volcanoes
47) A diamond gemstone and a cubic zirconia gemstone cut exactly the same
will
a) weigh the same
b) weigh different amounts, the diamond will be heavier
c) weigh different amounts, the diamond will be lighter
d) weigh different amounts, but it's not possible to say which will be
heavier.
e) weigh the same within the precision of the balance they are weighed
on.
48) Jewelers commonly use a test for distinguishing diamond from
imitations that relies on
a) hardness
b) R.I.
c) fluorescence
d) thermal conductivity
e) luster
49) The source rock for diamonds is called
a) granite
b)
kimberlite
c) kaesurtite
d) rhyolite
e) pipe rock
50) Gem synthetic diamonds are
a) available in large sizes, i.e. greater than 1 carat
b) identical in every aspect to natural diamond
c) have yet to made
d) common in today’s marketplace
e) not widely available
51) The cut proportions of a diamond have traditionally been based on measurements of
a) the number of facets
b) the height of the crown and diameter of the girdle
c) the girdle and table diameters, and the depth of the stone
d) the culet angle and girdle diameter
e) the height of the pavilion and the table diameter
52) Color in "colorless" diamonds is rated according to
a) the amount of yellow present
b) the amount of blue present
c) visual clarity
d) quality of surface reflections
e) presence or absence of a gray overtone
53) In the G.I.A. color grade scale, truly colorless diamonds receive a
grade of
a) A
b) Z
c) E
d) D
e) AAA
54) Assuming appraisers have a set of master stones and is proficient at
grading, they can determine the color grade of a diamond set in a ring to
within
a) one grade
b) two grades, if a microscope is available
c) three grades
d) four grades
e) they can't do it at all unless he takes the diamond out of the ring
55) The difference in color between an E and an F diamond is
a) so subtle that only a trained expert can see a difference
b) so subtle that it does not influence the value of the diamond
c) great enough to be visible to anyone looking at stones of these colors
d) not as important as a difference in VVS vs. VS clarity.
56) To accurately grade diamond clarity requires
a) a microscope and a set of master stones
b) a microscope, professional training, and substantial experience
c) good eyes and some experience
d) a microscope, professional training, and a set of master stones
e) a clarity grading instrument
57) The minimum weight for a 1 carat diamond is
a) 0.95 carats
b) 0.99 carats
c) 0.995 carats
d) 1.00 carats
e) 0.999 carats
58) A "light carat" is a term used for diamonds
a) that are not quite a full carat in weight
b) of poor cut, but weighing a full carat
c) of poor color, but weighing a full carat
d) of excellent clarity, weighing a full carat
e) having fewer calories than tastier, full carrot stones.
59) In diamond clarity grading, flaws or inclusion visible to the naked
eye in stones of a carat or less are given a grade of
a) I1, I2, or I3
b) VS1 or VS2
c) Z
d) SI1 or below
e) above SI1
60) Diamonds as an investment commodity are
a) a safe bet; prices can only rise because of the diamond cartel.
b) not a safe bet; diamonds are susceptible to the same supply and demand
forces as other commodities
c) attractive because there has always be a strong demand; prices can
only rise.
d) a safe bet if one buys only the very best stones and holds onto them
for several years before selling.
e) probably a better investment than most other things, like precious
metals, art work, stamps, coins, etc.
61) Flame fusion is a process used to
a) enhance the color of sapphires
b) grow opal in the laboratory
c) manufacture cubic zirconia
d) turn spinel into corundum
e) none of the above
62) Major producers of diamond today are
a)South Africa, Brazil
b) Borneo, China, Brazil
c)Brazil, India, US
d) Russia, Canada, Botswana
e) Zaire, South Africa
63) Gem synthetic diamond is
a) available and costs less than natural diamond
b) called cubic zirconia.
c) not widely available in sizes
over 1.5 cts.
d) easy to manufacture but currently very expensive.
e) has considerably different optical and physical properties than
natural diamond.
64) Color and clarity in "colorless" diamonds
a) can not be altered
b) can be altered but alteration can be easily detected.
c) can be altered in such a way that detection of the alteration is very
difficult for even highly trained people.
d) are the most important aspects in grading a diamond and evaluating its
worth.
e) are very subjective quantities that are extremely difficult to
quantify.
65) Flux growth is an important means of synthesizing
a) emerald
b) ruby
c) topaz
d) opal
e) a and b
66) The hydrothermal process of growing gem minerals uses
a) molten material that contains a flux
b) water vapor and seed crystals
c) a drip-by-drip accumulation of molten Aluminum oxide
d) no seed crystals
e) very high temperatures, above the melting temperatures of most
minerals
67) Corundum is found in
a) marbles
b) volcanic rocks
c) placer gem deposits
d) metamorphic rocks
e) all of the above
68) Separating natural from synthetic corundum commonly relies upon
a) a refractometer
b) heavy liquids
c) the naked eye
d a microscope
e) an x-ray radiograph
69) Of the following, which is not a technique used to enhance sapphire?
a) heating
b) irradiation
c) deep diffusion
d) flame fusion
e) filling
70) Natural diamonds are all
a) millions or billions of years old
b) found in South Africa
c) of gem grade
d) worth at least several hundred dollars per carat
e) treated to improve clarity before cutting into gemstones
Record whether each of the statements is True or False.
71) A retailer is legally obligated to disclose any and all treatment a
gem has been subjected to improve its appearance.
a) true b) false
72) Colored or "fancy" diamonds are always more expensive than white
diamonds.
a) true b) false
73) Muzo and Chivor are famous Colombian emerald mines
a) true b) false
74) Curved color zoning is a characteristic of natural sapphire
a) true b) false
75) Chrysoprase is a variety of gem quartz.
a) true b) false
76) Rainbow obsidian is a variety of man-made glass.
a) true b) false
77) Pegmatites are rocks that form from the dissolution of limestones
a) true b) false
78) A lode deposit is usually mined by washing gravel with water.
a) true b) false
79) Volcanic gems that are xenocrysts are minerals that crystallize from
the magma they are found in.
a) true b) false
80) The mixing of magmatic water and rainwater is necessary to form
hydrothermal vein deposits.
a) true b) false
81) The addition of heat to a gem-producing environment allows convection
and higher solubility of elements needed to make gem minerals.
a) true b) false
82) Most gem synthesis techniques closely resemble natural processes of
gem formation.
a) true b) false
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