Half-Moons

(via Diamond Cuts in Historic Jewelry:1381-1910) Herbert Tillander writes:

A Half-Moon is basically one half or less of a round-cut gem, with the straight side deeply faceted to produce a balanced and attractive design. Like other fancy outlines, it must first have been suggested by irregular rough the shape of a half-moon, a shape which was believed to have talismanic powers.

Half-Moons are rare both in surviving jewels and in contemporary illustrations. Clearly, there was little incentive to fashion such a shape, a wide triangle usually being preferred. Nearly all the examples I have seen have been of Italian origin. While this cannot be pure coincidence, I have been unable to discover any reasonable explanation. According to the eminent specialist Basil Watermeyer, the Half-Moon ‘was probably born through being accidentally cleaved in the faceting process. When this happens on a round cut which is already far advanced, there is just nothing else which can be done. Often rough stones have deep fractures through the side and no other cut but the half-moon can be adapted to it....It is essential that faceting designs have a meeting point midway between table rid and girdle so that the meet of the star and top half can link up.’