Indian Gemological Identification

4C's of Diamonds

Rough Diamonds are sorted((Graded) depending on their crystal shape, size and clarity before being sold to be cut and fashioned. In assessing the value of a cut diamond when buying or selling those in the jewellery trade will take four attributes into account. These are generally referred to as the 4 C’s.

* Colour

* Cut

* Carat and

* Clarity

Colour :

You may have heard a so-called ‘perfect’ diamond being referred to as a ‘D flawless’. This is the terminology used to describe a diamond with a colour ‘D’(the whitest and cleanest colour) and totally clear without any flaws or imperfections. Most diamonds, however, have a slight hint or tinge of colour, usually yellow or brown. Without training and practice, the very slight differences in colourles diamond are difficult to see. It is not until about grade M that the yellow tinge becomes more obvious. The bright coloured diamonds(including pink, yellow, blue and green) are called fancy coloured diamonds. They are described using different schemes.

Cut :

The shape of the cut and make of the cut(how exactly it has been cut) are taken into account when assessing the cut of a diamond. The round brilliant cut is the most popular cut for a diamond. The angles and dimensions of an ‘ideal brilliant’ are worked out mathematically(for example, by diamond cutter Marcel Tolkowsky in 1919), to give the best possible shape and number of flat polished faces(facets) to ensure that light which enters the gemstone is reflected back towards the eye of the viewer. A well-cut brilliant diamond will sparkle showing flashes of all the colours of the rainbow(firm); a badly cut one will appear dull and lack fire.

Carat :

The unit of weight used to measure diamond is the carat (0.2g) (g = gram). The name is thought to have been derived from the carob, which is now used as a chocolate substitute. Each seed or bean of the carob is nearly identical in weight. Traditionally, a one carat diamond was the same as the weight of one carob bean, though it is now standardised as 0.2 g. In the Far East, rice was used as a comparison and one carob bean equalled four grains of rice. There are 100 points in a carat, so half a carat diamond will weight 50 points.

Clarity :

A diamond’s clarity is based on the size, number, and location of internal and external characteristics. Known as inclusions, internal characteristics include crystals, clouds, and feathers. External characteristics, or surface irregularities, are called blemishes. As most inclusions can’t be seen by the naked eye, gemologist use a ten-power (10x) microscope to rate diamond’s clarity.

And then there's the "Fifth C":

- Certificates