Edwardian Black Opal, Diamond, Platinum, Gold Necklace, J.E. Caldwell  Co. The necklace features a pearshaped black opal cabochon measuring 18.00 x 12.00 x 4.70 mm, set in gold, enhanced by European and fullcut diamonds weighing a total of approximately 0.45 carat, set in platinum, marked JEC  Co. for J.E. Caldwell  Co. Gross weight 6.38 grams. Pendant Dimensions 158 inches x 1116 inch Chain Length 15 inches. Listed at Heritage Auctions, via Stonefinder.