|
A
 |
abraded
culet
|
A chipped
or scratched culet. Can be caused by contact with another
diamond. |
abrasion
|
A bruise or
scratch on the surface of a stone. |
AGS
|
American
Gem Society. Professional organization formed in 1934 by
several independent jewelers and the founder of the
Gemological Institute of America (GIA). The AGS is
dedicated to setting and maintaining ethical standards and
practices within the industry. |
Antwerp
|
Perhaps the
most noteworthy and versatile diamond-cutting center in the
world. All sizes and shapes of rough diamonds are cut in
Antwerp. |
appraisal
|
A monetary
evaluation, usually performed for insurance purposes by a
gemologist. Appraisals should describe the piece in detail,
including color, clarity, proportions, stone sizes, flaws
and other distinguishing characteristics. |
|
B
 |
baguette
|
A
rectangular cut stone with squared corners. |
bearding
|
Small
feather-like cracks along the girdle of a diamond. |
bezel
|
Outer ring
of a watch case, usually designed to hold the crystal, that
may also be used for advanced functions like diving timers. |
bezel
setting
|
Holds a
gemstone in place on all sides at the girdle, creating a
smooth, metal halo flush with the stone's crown. Bezel
settings often give the impression of a larger stone. |
blemish
|
A flaw,
spot or scratch on the surface of a gemstone. |
blood
diamonds
|
Information and answers about blood diamonds |
brilliance
|
The
intensity and amount of light reflecting from inside a
diamond or gemstone. |
 |
brilliant cut
|
The most
common style of cutting for diamonds and colored stones.
Brilliant cuts may be round or fancy and must have 57 or 58
facet cuts. |
|
C
 |
cabochon
|
A gemstone
cut that creates a dome shape with no facets. |
caliper
|
Instrument
for determining the thickness or diameter of a gemstone. |
carat
|
One of the
"Four Cs". Metric unit of weight for diamonds and
gemstones. One carat equals 200 milligrams or 0.2 grams. |
certification
|
American
Gemological Society (AGS),
Diamond High Council (Hoge Raad Voor Diamant;
HRD), European Gemological Laboratory (EGL),
International Gemological Institute (IGI),
and the Gemological Institute of America
(GIA), to name a few.
|
clarity
|
One of the
"Four Cs". Measures the degree to which a gemstone is free
from flaws. A clarity scale is used to grade flaws in
gemstones. The scale ranges from FL (Flawless) where there
are no visible internal or external flaws to I3, where many
imperfections are visible to the naked eye. |
cleavage
|
Tendency of
a crystalline material to break in certain directions, often
along a grain or crystal face. |
cloud
|
Group of
tiny white inclusions in a diamond. |
color
|
One of the
"Four Cs". In diamonds, the color scale ranges from D
(colorless) to Z (yellow). In colored gemstones, the
grading scale differs widely depending on the type of stone. |
comfort
fit
|
Ring design
in which the edges of the shank are rounded for maximum
comfort. |
crown
|
The facets
or portions of a gemstone located above the girdle. |
culet
|
A small
polished facet located at the sharp point or base of a
faceted diamond or gemstone. |
cultured pearl
|
Pearls
created by the artificial introduction of a mother-of-pearl
irritant into an oyster or other mollusk. Cultured pearls
generally have thinner nacre and lack the luster of a
natural pearl. |
cut
|
One of the
"Four Cs". Perhaps the most important factor in determining
the value of a diamond or gemstone. The cut refers to the
geometric proportion that dictates the reflection and
refraction of light within a stone. |
|
D
 |
depth
|
The
distance from a gemstone's table to its culet (top to
bottom). |
depth
percentage
|
The
measurement of a gemstone's depth (top to bottom) in
relation to its diameter. Depth percentage is primarily
responsible for refraction, which produces the fire or
sparkle in a gemstone. |
Diamond
Gauge
|
A
mechanical device used to determine the precise measurements
of a gemstone. |
DiamondLite
|
Instrument
for color grading diamonds using visual comparisons to
master diamonds. Trademark, Gemological Institute of
America. |
dispersion
|
The
separation of white light into the full color spectrum.
Often described as the "fire" or sparkle when discussing
diamonds. |
|
E
 |
emerald
cut
|
Step cut
gemstone (most often rectangular) whose corners have been
cut off. |
extinction
|
Dark or
black spots in colored stone. |
eye-clean
|
Gemstone in
which the flaws cannot be seen without a 10x loupe. |
|
F
 |
facet
|
Flat,
polished surface or plane on a gemstone. |
 |
faceted
girdle
|
Girdle that
has been cut with facets. |
fancy
shapes
|
A gemstone
shape other than round. |
feather
|
Internal
flaw (inclusion) that has a feathery appearance. |
findings
|
Small,
pre-fabricated parts of jewelry such as clasps, settings,
etc. |
fire
|
The
sparkles of flashes of spectral colors emitted from diamonds
and other gemstones. |
flaw
|
General
term used to refer to internal or external characteristics
of a gemstone (i.e., inclusion, fracture, etc) |
flawless
|
Term used
to describe a gemstone that lacks discernable internal or
external blemishes when viewed by a gemologist using no less
than 10x magnification. |
fluorescence
|
Luminescence that appears when certain diamonds are exposed
to ultraviolet light. |
fracture
|
Cracks,
feathers or chips in a gemstone. |
full
cut
|
Gemstone
with 58 facets. |
|
G
 |
gemologist
|
Gemstone
specialist trained in gem identification, grading and
appraising. |
gemology
|
Science and
study of gemstones. |
GIA
|
Gemological
Institute of America. Non-profit organization specializing
in grading diamonds and gemstones. Widely held as the
premier laboratory for gemological grading. |
girdle
|
The narrow
rim around a gemstone separating the crown from the
pavilion. |
gold
|
Gold,
one of the most precious of metals, is virtually
indestructible. The karat mark on a piece of gold jewelry
indicates how much pure gold that piece of jewelry
contains. The system of measuring with karats is based on a
scale of 24, with 100% gold equaling 24 karats. Since 24k
gold is usually considered too soft to be used in jewelry
making, gold is alloyed with other metals to strengthen and
harden it. |
gold
filled
|
Metal
covered by a thin layer of gold that is at least 10k and
1/20th of the total weight of the piece |
gold
plated
|
Virtually
the same as gold filled, except gold plated items may have a
layer of gold that is less than 1/20th of the total weight
of the piece |
grading
|
Valuing a
diamond using master stones. |
|
H
 |
head
|
Portion of
a jewelry item that holds the stone. |
|
I
 |
imperfection
|
General
term used to refer to internal or external characteristics
of a gemstone (i.e., inclusion, fracture, etc) |
inclusion
|
Visible
internal flaws in a gemstone, including fractures,
crystalling abnormalities, and foreign objects. |
irradiation
|
Treatment
performed on gemstones and even pearls to enhance color. |
|
K
 |
karat
|
Standard
measure of gold purity. One karat is 1/24th pure. |
|
L
 |
laser
drilling
|
Technique
used to enhance a stone's clarity by allowing for the
introduction of bleaching agents or other enhancing agents. |
leakage
|
Light
leaving, or escaping, through the facets of fashioned
gemstone. |
Leveridge gauge
|
A
millimeter gauge used to measure both mounted and unmounted
stones. |
loupe
|
Small
magnifying glass, often held in the eye socket, used for
analyzing gemstones. |
luster
|
The
appearance of a material's surface, as determined by the
quantity and quality of light reflected. |
|
M
 |
marquise
|
Oval shaped
gemstone with ends sharpened to points.
 |
master
stones
|
A set of
diamonds used to grade the color of other diamonds. |
milgrain
|
Tiny beads
of metal used to decorate bands of metal |
Moh's
Scale
|
Scale used
to measure gemstone hardness. Scale ranges from 1 to 10. |
mounting
|
Method of
holding gemstones in place (i.e., prongs, bezels, etc) |
|
N
 |
nacre
|
Crystalline
substance that forms a pearl when secreted by a mollusk in
response to an irritant. |
|
O
 |
off
color
|
A stone
presenting any semblance of undesirable color. |
oiling
|
Temporary
treatment used to enhance the color of a gemstone. |
opera
|
A strand of
pearls 32 inches in length. |
|
P
 |
pave (pah-vay')
setting
|
Style of
setting small stones as close together as possible. Stones
are set into drilled holes and metal beads are pushed over
to hold the stone. |
pavilion
|
The portion
of a gemstone located below the girdle. |
percussion mark
|
Indentation
or bruise on the surface of a gemstone caused by contact
from a pointed object. |
pit
|
Indentation
on the surface of a diamond or gemstone. |
platinum
|
Platinum is
pure, rare, eternal and versatile. Platinum's purity endows
it with a brilliant white luster. This helps to reflect the
true radiance of diamonds. It is at least 95% pure and it
does not fade or tarnish and keeps its look for a life
time. Platinum's purity makes it hypoallergenic and ideal
for those with sensitive skin.
|
plot
|
Diagram of
a gemstone's clarity characteristics. Generally performed
during an appraisal using magnification. |
point
|
One-one
hundredth (0.01) of a carat. |
princess
|
A strand of
pearls 18 inches in length. |
princess cut
|
Square cut,
brilliant gemstone.
 |
prong
|
Metal
"finger" bent around the girdle of a gemstone to hold it
securely in place. |
proportion
|
Mathematical representation of a gemstone's overall
symmetry. |
|
R
 |
re-cutting
|
Refinishing
a polished stone in order to improve the stone's clarity,
proportion or other imperfection. |
reflection
|
Light
rebounding off the polished surfaces of a gemstone. |
 |
refraction
|
Bending of
light waves. When white light is refracted, a full spectrum
of color appears, as in a prism. |
rope
|
A strand of
pearls 40 inches in length. |
rough
|
An uncut or
unpolished diamond or gemstone. |
|
S
 |
setting
|
Method of
holding gemstones in place (i.e., prongs, bezels, etc) |
shank
|
Part of the
ring that encircles the finger. |
single
cut
|
A simple
form of cutting that has a table, approximately 16 facets
and rarely a culet. |
solitaire
|
Ring
containing a single diamond or gemstone.
 |
symmetry
|
Uniformity
of a gemstone's cut, including the shape and placement of
facets. |
synthetic stone
|
"Man-made"
gemstone grown in a lab. |
|
T
 |
table
|
Largest
facet on a gemstone. The table sits atop the crown and
allows light to enter and exit, creating the stone's
brilliance. |
 |
table
percentage
|
Diameter of
a gemstone divided by the size of the table. |
Tolkowsky, Marcel
|
Mathematician that defined the proportions necessary for
maximum brilliance from a round diamond brilliant cut |
|
U
 |
ultrasonic
|
Cleaning
device for jewelry that removes dirt through the use of
ultrasonic waves. Note: Certain gemstones may be damaged
by an ultrasonic cleaner. |