Jewelry Dictionary

A

abraided 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.
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.
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 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

imperfectionGeneral term used to refer to internal or external characteristics of a gemstone (i.e., inclusion, fracture, etc)inclusionVisible internal flaws in a gemstone, including fractures, crystalling abnormalities, and foreign objects.irradiationTreatment 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 gem stones.
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)
Style of setting small stones as close together as possible. Stones are set into setting 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
Precious metal that is far harder than gold. Platinum does not tarnish and is hypo-allergenic.
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

recutting
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.