Gump's Black Onyx, Diamond, 18k Yellow Gold Crab Brooch. Designed as a crab, the shell comprised of a black onyx cabochon measuring approximately 15.2 x 19.5 mm, the eyes completed by two full-cut diamonds weighing a total of approximately 0.15 cttw., set in an 18k yellow gold mounting measuring approximately 32 x 36 mm. {Gross Weight: 9.9 dwts}