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Diamond is pure carbon that has crystallized in the isometric (cubic) configuration. It is the only single-element gem that exists on this planet.
Diamonds are commonly judged by the "four Cs": Carat, Clarity, Color and Cut.
Carat (ct) is simply a measurement of weight in the metric system. Many confuse the other term karat as used in the US for denoting gold purity, with the carat weight measurement. The carat was adopted in the USA in 1913, and today it is the international standard in most countries. The carat is defined as exactly 1/5th of metric gram or 200 milligrams. There are about 142 carats in an ounce and about 2,272 carats in a pound. A point is 100th of a carat (or 2 mg), which means there are 100 points in a one-carat-even stone.
Clarity is the quality of state of being clear.
Diamonds basically have two types of flaws. They are categorized as:
Abraded or rough culet — this is considered to be a minor flaw when the culet has been poorly finished or chipped.
Girdle roughness — this defect appears as criss-crossed lines being slightly chipped and having a brighter and duller finishing.
Cavities or pits — these defects, if found to be deep on the table facet would reduce the stone grade.
Nick — is usually found on the girdle as a small chip, which is result of wear.
Polishing lines — found on many diamonds. result of the polishing wheel not being properly maintained.
Scratches — considered to be minor defects.
A small natural — this appears to be like a rough, unpolished area and mostly occurs on the girdle. It looks like scratch or small triangle.
Colorless crystal — usually a small crystal of diamond and can also be of other mineral.
Dark spot — thin, flat inclusion or a small crystal inclusion.
Feather — a crack in the stone.
Growth of grain lines — these usually appear as a group of 2 to 4 pale brown lines and they instantaneously appear and disappear.
Laser treatment — a black spot on a stone can be practically removed when subject to laser treatment. Laser holes can be spotted and appear like straight fine white threads.
Pinpoint — this is usually a whitish (sometimes dark) dot that small and difficult to see.
IF — Internally Flawless (free from internal blemishes visible under 10X magnification (small external details tolerated).
VVS1 — very very slightly included (inclusions and/or external blemishes very difficult to locate under 10X magnification).
VVS2 — very very slightly included (inclusions and/or external blemishes very difficult to locate under 10X magnification).
VS1 — very slightly included (inclusions and external blemishes difficult to locate under 10X magnification).
VS2 — very slightly included (inclusions and external blemishes difficult to locate under 10x magnification).
SI-1 — slightly included (inclusions and external blemishes easy to locate under 10X magnification).
SI-2 — slightly included (inclusions and external blemishes easy to locate under 10X magnification).
SI-3 — slightly included (inclusions and external blemishes easy to locate under 10X magnification).
I-1 — imperfect (inclusions and external blemishes easy to locate with naked eye).
I-2 — imperfect (heavy inclusions very easy to locate with the naked eye).
I-3 — imperfect (heavy inclusions very easy to locate with the naked eye).
A diamond's color is graded on an alphabetical scale from D-Z, with D being absolutely colorless and Z being light yellow. The color difference can be so subtle, they are impossible to determine by the untrained eye. Beyond Z, a diamond is considered to be exotic or "Fancy" color.
The cut of diamond is the key that unlocks the hidden beauty within a piece of rough.
A diamond's cut will most certainly influence its fire (the lovely rainbow colors that flash from within) and brilliance (the liveliness and sparkle), as well as its perceived size and, even to some degree, its apparent color. Different cuts reflect light in different angles. A diamond must be cut in a geometrically precise manner to maximize its brilliance:
Many people confuse cut with the shape of a diamond. However the cut and the shape should be clearly distinguished.
