Cut

Cut refers to the shape and proportions of the diamond as well as the angles of its faceting, all of which combine to determine how much light is reflected back to the eye of the beholder. The dimensions given on the certificate of a diamond can tell only part of the story. The only way to truly evaluate a diamond is to examine it in person.

Proportions

It is in the hands of the master diamond cutter to bring out the scintillating fire of a diamond. Well cut diamonds reflect the maximum amount of light, through the diamond from one mirror-like surface to another, dispersed through the top of the stone. Diamonds cut too shallow or too deep lose light that spills through the side or bottom. Consequently, a poorly proportioned stone is less brilliant and spectacular and accordingly less valuable.

Ideal proportions for a round diamond, for instance, are 57% Depth (the proportion of the total height of the diamond compared to the girdle diameter) and 59% Table (the proportion of the table size compared to the girdle diameter). By definition, this is called the "ideal cut" and round diamonds showing these proportions are very expensive and highly sought after. This does not mean, however, that only ideal cut diamonds will show brilliance and fire! There are many other factors to be considered (such as color, clarity and carat size) and any diamond close enough to this measurements will bring the scintillating effect generally sought in a diamond.

The Ideal Cut concept, however, becomes very fussy with other shapes and it is for the expert gemmologist to judge the the beauty and value of a diamond.

Shapes

Shape refers to the inherent shape of the diamond. Among the most common shapes available on the market are the round cut, the marquise, the pear shape, the oval, the princess cut, the emerald cut, the heart shape and the radiant cut.