THE MOST USUAL METHOD of fashion- features, taking into account its color, fashioning a gem is to cut the surface into a clarity, and weight. He may, however, number of flat faces, known as facets. This gives the stone its final shape, or "cut". The craftsman, or lapidary, who cuts the stone aims to show its best have to compromise to retain weight and therefore value. The blue diagrams on the opposite page show the most popular cuts.
How A STONE IS FACETED
There are several stages in the cutting of a gemstone, each of which may be carried out by a different expert. In our example, a rough diamond crystal is fashioned into a brilliant- cut. This is the most popular cut for this stone because it maximizes the gem's naturally strong light dispersion. How- ever, because each stone is a different shape, or has imperfections within it, or because retaining the weight is of paramount importance, the cut in its ideal form (the "make") may not be possible. Nevertheless, the essential aim is to make the diamond bright and "sparkling", showing flashes of color called fire. To this end, the size, umber, and angles of the facets are mathematically calculated. The rough crystal is swan or cleaved to obtain a basic workable piece, then turned on a lathe against another diamond to give it a round shape. The facets are then cut and polished in stages, and the stone is given a final polish before mounting.
BRILLIANT-CUTS
The brilliant-cut is the most popular for diamonds, and for many other stones, particularly colorless ones. It ensures that maxi- mum light is reflected out through the front, giving brightness and fire. Variations in the outline give the oval, the pear- shaped pendeloque, and the boat-shaped marquise or navette.
STEP-CUTS
The step-cut (or trap-cut) shows colored stones to advantage, having a rectangular or square table facet and girdle, with parallel rectangular facets. The corners of fragile gems may be removed, making octagonal stones - as, for example, in most emeralds.
MIXED-CUTS
Mixed-cut stones are usually rounded in outline, with the crowns (above the girdle) cut as brilliants, and the pavilions (below the girdle) step-cut. Sapphires, rubies, and most transparent colored stones are cut in this style.
FANCY-CUTS
These have several possible outlines, such as triangular, kite- shaped, lozenge- shaped, pentagonal, or hexagonal. The cut may be used for rare gems, or to make the most of a flawed or irregularly shaped gem.
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