Square Brilliants

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

The first commercially produced Brilliants were rounded and derived from dodecahedral crystals, or were refashioned from Burgundian Point Cuts or Pointed Star Cuts. They became so popular that craftsmen had to find ways of adapting the design to octahedral rough (of which there was already a far greater supply), and applying the same type of faceting to square outlines without too much loss of weight. The result was the Square Brilliant, a very slightly rounded gem with sharp corners and obvious four-part symmetry in the main facets—a reversion in style from the Baroque to the Renaissance.