Antique Art Deco Platinum 18k Yellow Gold Diamond Onyx Cross with Original Chain. This beautiful antique cross has a unique philagree design with 43 diamonds and a large polished carved onyx. The front of the cross and the chain is done in platinum. The back of the cross is 18k yellow gold. The 43 diamonds are old rose cut diamonds. They average I color SI- 1 clairty. The chain in original to the cross. These pieces are made c. 1920. The cross alone measures 2 - 3/4 inches high by 7/8 inch wide. The chain measures 15 inches long.. The necklace and the cross are in excellent condition. They look lovely when worn together. Weight 10.2 grams.