gemology Flashcards
1
Q
Light to dark, slightly pinkish
orange, reddish orange, yellowish orange.
A
Malaya
2
Q
Medium to dark reddish
orange, red through slightly purplish red,
colourless (rare).
A
pyrope
3
Q
Light to dark purplish red
through reddish purple
A
rhodonite
4
Q
yellowish orange to reddish
orange.
A
spessartine
5
Q
blanket term essentially used
to describe two types of gem-quality
metamorphic rocks: jadeite jade and
nephrite jade.
A
Jade
piedra de hijada,
referring to the stones’ shape as they
were found, resembling kidneys
6
Q
term in china for nephrite jade
A
yu
6
Q
green colour sometimes referred to as
A
“Imperial jade,”
known in China as “fei cui”
7
Q
considered a 12th wedding
anniversary gemstone.
A
Jade
white, green, yellow to reddish orange,
brown, grey, black, light purple.
8
Q
. Treatment with acid
followed by polymer resin impregnation
is referred to a
A
“B jade”
9
Q
The classic and most important source
of jadeite is
A
Myanmar (Burma)
9
Q
an
amphibole aggregate rock essentially
composed by actinolite-tremolite
A
Nephrite Jade
9
Q
The pure white varieties, known in the
trade as
A
“mutton fat jade”,
9
Q
first discovered near
Pala, in California’s San Diego County, a variety of the mineral
spodumene, a source for lithium which
was often used for industrial purposes. Delicacy and subtlety of colour are this
gem’s most notable attributes, making
it an excellent choice for eveningwear,
A
Kunzite
10
Q
chromiumbearing variety, called
A
hiddenite
11
Q
referred to by them as
“heaven’s stone.” Pharaoh Cleopatra VII had
a particular affinity for it shadow makeup. Further, it was used as a
blue pigment (called ultramarine) for many
centuries. described as
sapphirus
A
Lapis lazuli
12
Q
Localities Lapis lazuli
A
Afghanistan’s mountainous Northeastern area of Badakhshan, notably in
Sar-e-Sang, is the world’s most famous
locality
13
Q
Because of a work of fiction by Sir Walter
Scott, “Anne of Geierstein” written in
1829, attributing “enchanted powers” unlucky gem
A
Opal
14
Q
where the vast majority of the world’s
opal is mined, the gem
A
Australia
15
Q
An opal seam in the
matrix host rock where it formed, namely
ironstone. These can be very thin but still
exhibit extraordinary play-of-colour.
A
Boulder opal
16
Q
An absorbent variety
of opal that may have play-of-colour.
Some material may appear as common
opal when dry, but which develops
play-of-colour phenomena when
immersed in liquid.
A
Hydrophane
17
Q
birthstones for the
month of October, 14th wedding
anniversary
A
Opal
18
Q
A milky, green opal found in Tanzania is
called
A
prase opal
19
Q
Because of its water content, opal
is sensitive to heat and temperature
changes. Opal may develop a network
of tiny fissures over time, or if subjected
to heat or pressure. These fissures are
referred to as
A
“crazing”
20
Q
remains among the most
important biogenic gem products
in jewellery
A
Pearl
21
Another form
of hardened tree resin is called
immature, or pre-fossilized amber.
copal
22
Heating in low temperature is used
to modify clarity, alter colour and may
cause some inclusions to expand, creating
spangled, disc-like inclusions, known in
the trade as
sun spangles or sun sparks
23
amber where
Dominican Republic, Baltic Sea
24
Coral
Mediterranean Sea, and the Eastern
Atlantic Ocean
25
gem exudes a
soft, oily appearance; comparable to the
deep greens you might see in olive “containing rays of sunshine.” . Egyptian slaves are said to
have discovered the first source for it at
Zabargad, a desolate island in the Red
Sea
has been found in a particular type of
meteorites, a pallasite from Argentina
birthstones for
August. It is also a 15th wedding
anniversary gemstone.
Peridot, a variety of olivine, forms in
the orthorhombic crystal system
26
, more recently,
Pakistan are sources that continue to
provide exceptional gems of significant
size, and exceptional colour, often over
ten carats.
Myanmar (Burma) and
Egypt (St John’s Island) is the classic
source, though it is no longer a
commercial producer of the gem.
Myanmar (Burma) is considered a
classic source too
27
A common inclusion scene in peridot is
called a o its similarity
with the pond plant
“lily pad”
28
Dr. Eduard Gübelin, v“jack of all trades.” Yet it is found on
every continent on Earth, standing in as
one of the world’s most plentiful minerals t gazing into
a large round crystal ball gave clairvoyants
an ability to “see” the future.
quartz
29
proved
crystal quartz to be a mineral, rather than
permanent ice. His book, Pseudodoxia
Sir Thomas Browne
30
Colourless quartz with bold and colourful
inclusions of another mineral (such as
hematite, goethite, mica or
rutile) is increasingly used in jewellery.
31
The transparent brown coloured variety
of this mineral is called
smoky quartz
morion
There is also
a small amount of natural green quartz
available, called prasiolite, located in the
Faroe Islands
32
green in appearance and its aventurescent
effect is generally less pronounced than in
glass. v
Aventurine quartz
33
Rutilated and tourmalinated quartz (also
called
sagenitic quartz)
34
sometimes regarded as
an alternate birthstone for the month
of January, along with garnet.
Rose quartz
35
s collected
in antique jewellery – especially Scottish
jewellery, due to its historical significance.
Smoky quartz
36
“pigeon’s blood”
where large red
spinels were called “balas”
famous Black Prince’s Ruby, a 170 carat
gem that graces the Imperial State Crown
of the United Kingdom, nestled next
to the famous Cullinan II diamond, is
actually a spinel. W
e birthstone for the month
of July. The 15th and 40th wedding
anniversaries are celebrated
Ruby
37
has produced
a standard of quality by which ruby from
other localities is often measured, the
term “Burmese ruby”
Myanmar (Burma)
38
Star ruby results when intersecting rutile
needles it contains form the phenomenon
called
asterism.
39
Conversely, the ancients called
the today’s sapphire
hyacinth,
40
e birthstone for the month
of September. It is used to celebrate 5th
and 45th anniversaries. Cause(s) of colour: Blue: iron and
titanium performed on low quality
sapphire material from Sri Lanka, known
as geuda n, haziness is not only expected
– it is desired, and that is in the finest
sapphire from Kashmir. The haziness
(often referred to as sleepiness) acts
to diffuse light and colour, resulting in
magnificently even blue colouration.
Sapphire
41
historic sources for sapphire and produce
some of the world’s finest gems
Sri Lanka and Myanmar (Burma)
Kashmir has
emerged as the preeminent source for
blue sapphire, especially in the late 19th
century. Sri Lanka is the classic source
for padparadscha sapphire, though other
sources also now produce mixes of pink
42
eferred
to as “balas ruby” Badakhshan set in the crown of
Queen Victoria is the so-called Timur
Ruby, a 361 carat gemstone that is also
a spinel. Among the
Iranian crown jewels is one named the
Samarian Spinel. Weighing approximately
500 carats, it is thought to be the world’s
largest fashioned spinel great
Indian Mughal gem collector, Jahangir,
had once owned it is singly refractive, meaning that light
passing through it in any given direction
is not split into two rays. Spinel has a high
refractive index, an one of the birthstones for August
and it is used to commemorate a 22nd
wedding anniversary Pamir Mountains
in Central Asia is rare and collectible, as
is spinel from Myanmar (Burma Tajikistan – especially in the region of
Badakhshan, in the Pamir Mountains,
remains a classic source for the gem and
the main source for large sized gems
Spinel cubic crystal system,
43
variety of the mineral zoisite,
is a relatively new gemstone on the
market so it does not share the depth
of history presented by other gems Henry Platt, vice president of Tiffany &
Co., who had been shown the material
and admired it, was the first to call it Merelani been added as a
birthstone for the month of December,
along with zircon and turquoise.
“tanzanite,”
44
other colours are also mined in
Merelani, including pink, purple, yellow,
and green. These are sometimes referred
to as
“fancy tanzanites” in the trade. While
they are all zoisite, only the deep purplishblue colours can be called tanzanite.
45
and refers to the
gems from the island of “Topazios,” which
is known today as Zabargad
poem Neruda in its purest colourless state was
sometimes mistaken for diamond in
ancient times. The so-called “Braganza
Diamond,” 1680 old-carats has perfect cleavage in one
direction, so carvings are rare considered rare in natural pink
and orange colours; less so in blue colours
that are generally treated from colourless
to achieve saturated blue hues
Topaz is a birthstone for the month of
November. Blue topaz is given for a 4th
wedding anniversary and Imperial topaz is
given for a 23rd anniversary orthorhombic crystal system Pink and red topaz
is principally coloured by chromium.
Brazil – particularly the area near the
town of Ouro Preto in Minas Gerais,
produces much of the world’s supply of
classic yellow to orangey pink colours. colourless to pale blue range.
Schneckenstein, a village in Germany, was
a major classic source of European topaz
in the 1700s. Pakistan produces some of
the strongest pink to reddish colours at
Katlang, near Peshawar
46
, Eduard Gübelin, referred to it as
a “crystallized kaleidoscope group of closely related
minerals composed of several species and
varieties m red to violet can also be
bicoloured, colourless or black most
of the gem tourmaline used in jewellery
today belongs to the elbaite, rossmanite,
fluor-liddicoatite and dravite mineral
species, which exhibit the strongest and
brightest colours. nickname aschentrecker, meaning “ash
puller.” nickname aschentrecker, meaning “ash
puller.” one of the birthstones for
the month of October, along with opal.
Tourmaline trigonal crystal system, abundant fluid inclusions,
which look like thin, threadlike and
elongated fingerprints exhibit cat’s-eye phenomena. .
Brazil remains the world’s largest producer
of tourmaline in all colours. The States of
Paraíba and Rio Grande do Norte have
produced Brazil’s most coveted cuprian
(copper bearing) tourmaline.
47
Rubellite: Pink to red range, may also be
brownish, orangey, or purplish.
Verdelite: Yellow green to bluish green.
Indicolite: Violetish to greenish blue.
Paraiba tourmaline: Vividly coloured
blue to green gems in which the unusual
hues result from traces of copper and/or
manganese.
Dravite: Yellow to brown; the bright yellow
colour has been called “canary tourmaline”
in the trade.
Achroite: Colourless
Parti–colour: Two or more colours (if
only two colours are seen, these gems are
called bi-coloured).
Watermelon: Pink centres with green
around the outer margins of the stone.
Chrome tourmaline: A deep, solidly green,
chromium-containing gem.
Cat’s eye tourmaline: Tiny hollow growth
tubes in some cabochon-cut tourmaline
cause a cat’s eye effect in direct lighting.
Liddicoatite: This is the fluor-liddicoatite
species of tourmaline, a calcium-rich,
lithium tourmaline that was named in
1977 in honour of one of GIA’s founding
fathers, the noted gemmologist, Richard
T. Liddicoat. This is a usually a parti-colour
tourmaline par excellence and often
exhibits many colours in strongly zoned,
geometric patterns.
48
”, derives from the
Brazilian state in which particular copperbearing tourmalines were first found.
However, it soon became a widespread
descriptor for the saturated colours caused
by copper and/or manganese, even those
found in different localitie
“Paraíba
49
\ strong colour, especially
from sources that produced high qualities
for short times, such as Nigeria, is
collectible. Indicolite, sometimes also
called indigolite, that exhibits strong blues
are also very popular
Rubellite
50
Afghanistan is
known for a very bright blue green quality
of tourmaline, though it also produces
some green and pink material.
Tourmaline’s elongated, prismatic crystals
dictate how the gemstones are cut,
51
Excavations from
Pharaoh mummies dating up to seven
millennia ago contain evidence that the gem was highly prized
in ancient Egypt – both as a gemstone
and as an ornamental material. Successive
Egyptian dynasties since then used also
the gem as a symbol of good fortune, with
historical sources in the Sinai Peninsula
and in today’s Iran
China was a source for turquoise during
the time of Marco Polo’s travels, and he
found that turquoise beads were traded
and bartered all along the Silk Road. A
52
desired turquoise is described as the blue
of a robin’s egg, pale blue to blue-green
to dark blue
Deposits in China, for
example, are known to produce a light to
dark green turquoise with little or no blue
component.
53
one of the birthstones for
December, along with zircon and tanzanite.
It is also used to celebrate an 11th
wedding anniversary
Turquoise is a hydrous copper phosphate
mineral that crystallises in the triclinic
crystal system;
5 to 6
Some imitation
turquoise material is represented as
pressed or “reconstructed” turquoise. “Spiderweb” matrix, containing fine dark
lines with an attractive, even pattern
surrounded by deep blue turquoise
54
turquoise from Iran (Persia) was
historically a standard for the finest
turquoise, material from the United
States – specifically Arizona – has proven
to be a fine source as well.
The United States (mainly Arizona, New
Mexico, California and Nevada) and
Mexico are sources for material that has
been traded through the Americas for
centuries. Most of the world’s supply
of turquoise comes from the United
States and China today. Iran, notably in
Neyshabur, remains the classic source
for fine turquoise, though little material
is presently mined the
cut in cabochon
form. They are often fashioned as
free-form beads (Turquoise
beads may darken over time if they are
in direct contact with skin.
55
it has nothing to do
with cubic zirconia (a man-made product
that has been used as a diamond simulant extraordinary lustre, brilliance and fire, a
product of high refractive indices and very
high dispersion. is a birthstone for the month of
December, together with turquoise and
tanzanite tetragonal crystal system 6 for low type; 7.5 for
high type
zircon
56
has an un-altered crystal
structure, like most other crystalline gems.
hightype zircon
Low-type zircon is “metamict,” which
means the crystal structure has been
changed towards and amorphous state
by natural irradiation
57
gold
coloured, though, zircon is found in many
colours. A range of red to orange, yellow to
brown, and blue to green are found, though
natural blue zircon is quite rare.
double refraction, which is often easily
visible when looking through a gem’s table
with the naked eye
58
In metamict zircon, angular colour zoning
or angular markings can be seen, as well
as an unusual milkiness in some stones Apatite and garnet
crystals are sometimes found in zircon.
Zircon is sometimes collected in colour
groups to exhibit an array of colours,
and red zircon, especially in large sizes,
is particularly prized. Vivid blue colours
from Ratanakiri (Sri Lanka) are also highly
desirable. Some collectors buy metamict
gems that exhibit unique phenomenal
characteristics such as aventurescence
or cat’s eye. Cat’s eyes do occur in
included material but the eye is generally
indistinct
59
Cambodia, Sri Lanka, Myanmar (Burma),
Australia, Madagascar, Tanzania, China,
Brazil and Thailand are the principal
sources of zircon
Zircon is quite brittle and it
is recommended that zircon jewellery not
be subjected to rough wear because facet
junctions abrade over time with careless
use. Warm soapy water or a damp cloth
should be used to clean zircon. Ultrasonic
or steam cleaners should not be used.
60
