Worths Diamonds

Carat weight. It takes more than 250 tons of ore, blasted, crushed and processed to yield just one carat of rough diamond. And only about one fifth of all rough diamonds are suitable for gem cutting. A carat equals 200 milligrams, or 0.2 grams, and there are 142 carats to an ounce. This has nothing to do with the "Karat" weight of gold, which is actually a measurement of purity rather than weight. In fact, the gemstone "carat" comes from the carob seeds that were used to balance scales in ancient times.

This might sound pretty unscientific, but according to historians, it was remarkably accurate. The tiny horn-shaped seeds were so uniform in size and weight that even today's sophisticated scales can't detect more than one three-thousandth of an ounce difference between them.

Today of course, gemologists use sophisticated equipment to measure the size and weight of diamonds, assuring accuracy even when they are set in jewellery. This is vital because when mounted, one diamond may appear larger than another, although they actually weigh the same.

For jewellery purposes, carats are further divided into points. A one-carat stone equals 100 points. So a half carat stone may be referred to as a "50-pointer", a quarter carat, "25-points," and so on, Smaller stones used in pave or channel settings are sometimes called melee. In certificates, appraisals and receipts, the weight of your diamond should be written in carats, rounded to 1/1000ths, such as .25 carats, .50 carats, 1.20 carats, etc.

It's also important to know that diamond prices rise proportionately with the size of the stone. Because large diamonds are rare, they generally have a greater value per carat. For example, the price of a two-carat stone will be several times higher, than, say, four 50-pointers of equal quality.

Likewise, a diamond that hits the one-carat mark will be worth considerably more than a 95-pointer of the same quality.

But size alone means almost nothing without also considering cut, clarity and colour. Being big is not enough if the brilliance and purity are missing.