Diamonds have the ability to refract light at a higher degree than any other gemstone. The cleaner the stone the brighter the diamond will shine. The more of nature’s inclusions present in a diamond the less valuable the stone.

Clarity



Carat
The Carat. [15th century French word derived from the Greek word "keration", meaning “fruit of the carob” because carob beans were used as standard weights for small quantities.]
All Gemstones are measured in carats.
1 carat = 200mg (or 1/5th of a gram). This means that five 1 carat diamonds would weigh one gram.

 

Another unit of measurement used is the “point”. A point is one hundredth of a carat. 100 points = 1 carat. For example you could describe the weight of a diamond as 0.50 carats or as .50 points.

A 5 carat stone for example is worth more than five 1 carat stones that are otherwise of the same quality.
In order to weigh diamonds, we use very accurate weighing scales. Scales used to measure diamonds are so sensitive that the weighing pan is sometimes inside a glass case so that the reading won't be affected by any draughts in the room.

Hardness
Diamond is the hardest known natural substance. This hardness is exhibited in its resistance to scratching and the ability to scratch other materials. Steel and glass, for instance, can be scratched by diamond. The Mohs hardness scale was devised by the German mineralogist Friedrich Mohs and indicates the relative hardness of substances on a rating scale from 1 to 10 – diamond being assigned a value of 10.