Blemish: A flaw (scratch or 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.

Brilliant Cut: A brilliant cut is any cut that utilizes 58 facets. It can be round, oval, radiant, pear or heart shaped.

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

Center Stone: The central, dominant stone in a piece of jewelry set with multiple stones. Also described as the solitaire.

Clarity: A grade given to a diamond to describe how many inclusions the diamond has. The clarity scale ranges from Flawless (FL), meaning a diamond has no internal or external flaws, to Severely Included (I3), meaning a diamond has many flaws clearly visible to the unaided eye.

Cloud: A cluster of small inclusions 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, which has a distinct yellow cast. As the scale moves from D to Z, it indicates increasing levels of yellow and brown tone.

Comfort Fit: The rounded finish on a ring's interior, designed to provide additional comfort for long-wear.

Culet: The foundation facet of the diamond. The culets of older, European cut diamonds can be seen through the table of the diamond and appear as round, glassy discs. The preferred culet is visible only as a tiny focal point where the facets of the pavilion converge.

Cut: Commonly used to refer to both the shape of a stone (round, pear, oval, etc.) and the make (the exact geometric proportions to which a diamond is cut). The make of a stone is the most important factor in determining how much sparkle a diamond produces.

Cut, Ideal: Round diamonds that are perfectly proportioned (having depth percentages and table percentages that maximize fire and brilliance) and have high grades on polish and symmetry. These stones have had the finest craftsmanship to maximize the beauty of the diamond.

Cut, Very Good: Diamonds cut to fit very strict requirements for depth percentage and table percentage. These outstanding proportions maximize fire and brilliance in the diamond.

Cut, Good: Diamonds cut with acceptable, but not perfect, cut proportions. They generally have very good brilliance and fire and make excellent jewelry.

Cut, Fair: Diamonds cut to maximize the weight of the stone, generally at the expense of fire and brilliance. While less expensive than diamonds shown as having Good and Very Good cuts, they do not have the sparkle people expect from a diamond.

Cut, Poor: Poorly cut diamonds that look lifeless to the eye. These diamonds are not recommended for fine jewelry.

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

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

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

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

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. Strong fluorescence should be avoided, but faint fluorescence usually does not affect the appearance of a diamond.

Girdle: The narrow band around the width of a diamond. The setting usually holds the diamond around the girdle.

Head: Attached to the ring shank, the head of the ring holds the center stone or solitaire in place.

Head Shape: The head shape of any ring is determined by the shape of the gemstone that it is intended to hold. For example, the head that holds an ideal-cut diamond is round, where a head intended to hold a princess-cut diamond is square.

Head Size Range: Describes the different carat weights of diamonds that may be mounted into one particular head.

Inclusion: All but the most rare diamonds contain inclusions, which are created during the diamonds formation deep in the earth. Inclusions are trace minerals, fractures, and other imperfections in the stone that contribute to its unique fingerprint.

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.

Metal Type: Fine jewelry is generally designed in the precious metals gold, platinum and silver.

Pavilion: The bottom portion of a diamond, from just below the girdle to the bottom.

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.

Ring Setting: Collective term for the shank and the head of the ring before the center stone has been set.

Ring Size: A measurement, generally somewhere between 4 and 13, that is determined by the diameter of the finger which will wear the ring, that permits a ring to be easily slipped over the knuckle. To determine your ring size, see our ring guide.

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 stone set alongside or encircling a center stone.

Sparkle: The combination of fire and brilliance; the amount of light that reflects out of a diamond.

Symmetry: A grade given to the overall uniformity of a stone's cut. The scale for symmetry ranges from poor to excellent. Poor symmetry will hurt the sparkle of a diamond. Diamonds with symmetry grades of good to excellent are recommended.

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

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

Thickness: The measurement, in millimeters, that indicates the width of a band or shank.