As with all precious stones, the weight - and therefore the size - of a diamond is expressed carats. The word carat originated in a natural unit of weight: the seeds of the carob tree. Diamonds were traditionally weighed against these seeds until the system was standardized and one-carat was fixed at 0.2 grams (one fifth of a gram).

One carat is divided into 100 "points" so that a diamond of 25 points is described as quarter of a carat or 0.25 carats.

Almost all diamonds contain minute traces of non-crystallized carbon, the element form which they were born. Most are not discernible to the naked eye and require magnification to become apparent. Called inclusions, they are nature's finger print and make every diamond quite unique. However, the fewer there are, the rarer the stone will be.

Clarity, therefore, is the term that is used to indicate the extent to which the diamond you purchase is free of these natural phenomena.

There are three major international grading systems for classifying diamonds - GIA, CIBJO and HRD. A stone is termed flawless by the GIA if it is without inclusions internally or externally; the other systems use the term Loupe clean - internally flawless. Below this top grade, the grades are comparable.

It sometimes surprises people to learn that diamonds can cover the entire spectrum of colors. The majority, however, range from those barely perceptible yellow or brownish tint, up to those that are very rare and are described colorless.

Some even rarer stones are naturally colored and are often referred to as Fancies. These diamonds are only found very occasionally and can come in tints such as green, red, blue or amber.

Of all the 4 C'S, cut is the one most directly influenced by man. The other three are dictated by nature. The cut or make of a diamond will dramatically influence its fire and sparkle, for it is the cutters skill that releases its beauty.

It is the cut that enables a diamond to make the best use of light. 1. When a diamond is cut to good proportions, light is reflected from one facet to another and then dispersed through the top of the stone. 2. If the cut of the diamond is too deep, some light escapes through the opposite side of the pavilion. 3. If the cut is too shallow, light escapes through the pavilion before it can be reflected.