AGS
The American Gem Society, or AGS. This group is recognized by the jewelry industry as an authority for grading gemstones.

AGTA
The American Gem Trade Association is recognized in the jewelry industry as an authority for grading gemstones.

Bezel Set
Bezel set is the use of a metal tube that is wrapped around the stone. Metal is pulled down over the stone to hold it.

Blemish
A flaw, such as a scratch or an abrasion, on the surface of a diamond.

Brilliance
White light reflected up through the surface of a diamond. Brilliance is maximized by cutting a diamond to the correct proportions. See also Fire and Sparkle.

Brilliant Cut
A 58-facet round diamond.

Carat
A unit of weight for a diamond, equivalent to 200 milligrams, or 0.2 gram.

Center Stone
The central, dominant stone in a piece of jewelry set with multiple stones. In a ring set with one stone, the center stone is also called the solitaire.

Certificate
A diamond certificate is a blueprint of the diamond. It describes, maps and grades everything about the diamond including: proportions, color, clarity, shape, cutting style, carat weight, location, size, and type of inclusions, fluorescence, and other lab comments. It does not state the retail value of the stone. An appraisal is needed to confirm the full market retail value.

Channel Set
Channel set refers to the setting of gemstones in a grooved channel between two bars of metal. The stones are set flush to each other.

Clarity
A grade given to a diamond to describe how many inclusions are within the diamond. The clarity scale ranges from FL (flawless), meaning a diamond has no internal or external flaws, to I3 (severely included), meaning a diamond has many flaws clearly visible to the naked eye.

Cleavage
An internal imperfection which runs in the direction of the grain of the diamond. It sometimes extends to the surface of the diamond, or is "healed" inside the diamond.

Cloud
A cluster of microscopic white or crystalline inclusions or pinpoints inside a diamond.

Color
A grade given to a diamond to describe the color tones of the stone. The color scale ranges from D, meaning completely colorless, to Z, fancy yellow. As the scale moves from D to Z, it indicates increasing levels of yellow and brown tone.

Comfort Fit
The rounded finish on the inside of a ring’s band. This design does not pinch the skin of the finger as much as other ring bands and provides comfort for constant wear.

Crown
The edges of a gemstone above the girdle and surrounding the table. Colored light escapes through the crown in the form of fire.

Culet
A facet on the very bottom of a diamond. If the culet is medium to large, when the diamond is viewed from the table, it will look like there is a hole in the bottom of the stone.

Cut
Generally, cut refers to both the shape of a stone (round, marquise, princess cut, oval, etc.) and the proportions and finish of a diamond also known as "make". The make of a stone is the most important factor in determining how much sparkle comes from a diamond.

Depth
The height of a diamond (measured from the culet to the table).

Depth %
The height of a diamond (measured from the culet to the table) divided by the width of the diamond. The depth % is critical to creating brilliance and fire in a diamond; a depth % that is too low or too high will cause a diamond to lack sparkle.

EGL
European Gemological Laboratory. Widely respected in the trade offering independently grading certificates.

Eye-clean
A diamond that has no inclusions visible to the naked eye.

Facet
The flat polished surfaces on a diamond. A round brilliant diamond has 58 facets.

Feather
A common naturally occurring white feather shaped inclusion, which is not visible to the naked eye.

Fire
Colored light reflected from within a diamond. Fire is maximized by cutting a diamond to the correct proportions.

Fluorescence
A glow, usually of a bluish color, which emanates from certain diamonds when exposed to ultraviolet light. Faint fluorescence usually does not affect the appearance of a diamond. Strong, very strong and sometimes medium blue fluorescence may slightly improve the color appearance of diamonds rated "H" in color or below (I,J,K etc).

Fracture
An internal or external imperfection which may have developed three million years ago or last week as a result of trauma (usually a hard impact).

GIA
Gemological Institute of America, the single most widely accepted diamond authority. An independent, third-party grading service offering diamond grading certificates.

Girdle
The outermost edge of a diamond, it can be unpolished, polished, or faceted. Usually where the diamond is held in a setting.

Head
The part of the setting that holds the center stone or solitaire in place.

Inclusion
A naturally occurring imperfection often referred to as a feather, pinpoint or cloud in the diamond that may or may not be visible to the naked eye. Inclusions visible to the naked eye are usually graded SI2 clarity and below.

Invisible Set
Invisible set refers to a particular square cut of stone which has been cut with slats that are fitted into a metal grid formed by the mounting’s undercarriage. Each stone is "snapped" into its rail. Two or more row styles may be fashioned in this manner to emphasize an "all diamond" look. The stones on the outside are usually channel set in the mounting.

Make
The proportions to which a diamond has been cut. A good make will have proportions that maximize the brilliance and fire of a diamond. A poor make will lead to a diamond that has little sparkle due to the inability of the cut to properly reflect light.

Melee
Diamonds which weigh less than 1/5 of a carat (20 points) are known as melee. They are usually side diamonds or accent diamonds in a larger piece of jewelry.

Metal, precious
Three metals are generally used in fine jewelry: gold, platinum, and silver.

Millimeter
The unit of measure used to determine a pearl’s diameter, equal to about 0.04 inch.

Natural
An external characteristic on or near a diamond’s girdle, a natural is actually an unpolished portion of the "skin" of the rough diamond.

Pavé Set
Pavé set is a two-dimensional form of strip setting in a honeycomb pattern. The stones are patterned very closely together. The metal is pulled up to hold the stones. The only metal visible is what is actually used to hold the stones in place.

Pavilion
The faceted portion of the diamond which is below the girdle.

Pinpoint
A very small inclusion inside a diamond.

Point
A weight measure equal to one one-hundredth of a carat. (A 0.50 carat diamond is said to be 50 points.)

Polish
A grade given to the external finish of a stone. The polish scale ranges from poor to excellent.

Prong Set
Prong Set is the use of metal wire to hold a gemstone in place by tension. A notch is cut out on the inside of the prong to seat a stone into its place. The prongs are pulled over the top of the stone to hold it.

Ring setting
Collective term for the shank and the head of a ring which contains no center stone.

Ring size
A measurement, generally between 4 and 13, determined by two factors: the diameter of the finger on which the ring will be worn and the knuckle, which the ring must slip over comfortably.

Semi-Mount
Engagement rings set with only the side stones. The center stone is sold separately to accommodate the individual’s preference in the size, shape, etc. of the stone.

Shank
The part of the ring that encircles the finger. Strictly speaking, the shank of the ring does not include the head.

Side stone
A gemstone set alongside, or as part of a group of gemstones encircling a center stone.

Solitaire
A single diamond set in a mounting which shows off the simplicity and elegance of the diamond.

Sparkle
Refers to the brilliance of a diamond or the amount of light which reflects from a diamond. See also brilliance and fire.

Symmetry
The overall uniformity of the cut of a diamond. Graded from poor to excellent, it is based on the diamond’s proportions and the relation of one facet to another. Poor symmetry will hurt the sparkle of a diamond.

Table
The largest facet on a diamond, located on the top of the diamond facing out from the setting.

Table %
The width of the table divided by the total diameter of the diamond. The table % is critical to creating sparkle in a diamond; a table % that is too low or too high will cause a diamond to lack sparkle.