18k white gold spinel and diamond necklace

18k white gold spinel and diamond necklace from the IJC collection. The halo style necklace features a 1.46ct modified cushion shape violet purple spinel (AA quality, from Myanmar/Burma, natural unheated) that measures 7.00x6.13x4.47mm. The pendant top and profile are surrounded by a halo of small round diamonds (46=.23 carats, of G color, SI1 clarity). The necklace is secured on a 18k white gold wheat chain measuring .80 mm thick, is 18 inches in length, with a spring ring clasp. The entire pieces weighs 3.73 grams.