John Mawe,
A Treatise on Diamonds, and Precious Stones
(1823)
“ I received a large fragment of diamond, weighing above 12 carats: one end was foul and full of flaws; I split it off, and discovered the foul was owing to a triangular hole, the sides of which were covered with black earth. Yellow brilliants, if fine, are generally extremely lively, and suit the purposes of the jeweller in composing fancy articles. When of from one to two grains, they are usually from four to five pounds per carat; being inferior in value to the pure gem. ”
