Cut
The brilliancy of a diamond is determined by its size. If a diamond has nice colour and good clarity but is incorrectly cut, its appearance will suffer much. Gemologists agree that a diamond's most important characteristic is indeed its size. By size, we mean the finish, the dimensions, the light return to the eye, as well as the polishing and the symmetry of a diamond.
In effect, while we may consider ourselves familiar with the notions of purity and colour, rarely can the same be said about proportions of size. Yet, these are an essential factor of quality. Size proportions have a direct influence on a diamond's brilliancy and « fire ». Identically coloured, a well-proportioned diamond will be much more bright than its pure, but incorrectly cut counterpart. Moreover, a diamond with wrong proportions will be appraised according to ideal proportions. For instance, an incorrectly cut diamond weighing 1.30 cts could weigh 1.00 ct once it is well cut. The value of this diamond will therefore have to be appraised on 1.00 ct, as opposed to 1.30 cts.
There are many ways to cut diamonds: princess cut, emerald cut, pear shape, marquise, Asscher and cushion cut, to name only a few. Of all these cuts, it is certainly the brilliant cut that has been most studied. This is also the cut which provides the best light return to the eye. Still today, it is the Tovolsky technique, dating back to 1919, that allows the ideal transformation of a raw stone into a magnificent showpiece consisting of 58 facets (57 if we omit the culet).