A diamond and blue topaz ring in white gold defines wonderful splendor. 14K white gold/blue topaz. Imported. Diamond:42 ct. T.w. Size: 7. All gemstone carat weights (ct. T.w.) are approximate; variance may be .05 carat. Almost all gemstones and black diamonds have been treated to enhance their beauty and require special care. Photo may have been enlarged and/or enhanced. Ring Size Chart.