Hardstone Cameo, Diamond, Platinum-Topped Gold Brooch, circa 1900 The pendant-brooch features a carved sardonyx cameo measuring 31.00 x 21.00 mm, enhanced by European-cut diamonds weighing a total of approximately 0.50 carat, enhanced by rose and mine-cut diamonds, set in platinum-topped 18k gold. Gross weight 14.85 grams.