The weight of a diamond is measured in carats.
One carat = 0.2 grams and one carat equals 100 points. i.e 1/2 carat = 0.50 points, 1/4 carat = 0.25 points
All diamonds have traces of their growth history. In gem-quality diamonds, this usually means minute internal and external characteristics.
The clarity scale reflects the size, number, location and visibility of the characteristics when examined with a loupe under x10 magnification. The very best - and rarest - clarity is internally flawless. Most inclusions are not visible to the naked eye. Diamonds that have no inclusions visible to the unaided eye are usually more valuable.
Most diamonds are colourless to slightly yellowish. The colour grade is determined by comparison with a series of masterstones, the best grade being colourless D.
Diamonds can also occur in all sorts of colours, ranging from brownish to striking yellows, pink to purple, red and blue. These are called “fancy colours”.
The proportions of a diamond determine the brilliance and the fire of the diamond. The symmetry describes the
variations of the different parameters which define the proportions. The polish describes the finish of the facets.
Diamonds can be cut in various shapes (e.g. princess, pear or heart). The round brilliant is probably the best known shape.