Tanzanite & Diamond Ring 18kt Yellow Gold. This is a pretty little ring set with tanzanites and diamonds in 18kt yellow gold. The ring has three marquise cut tanzanites, medium to medium-light, grayish, Violet in color, weighing approximately 0.375cttw. There is also two diamonds weighing 0.02cttw. The ring was cast and handset, it is in very good condition. Ring size is 7 1/2, it is hallmarked: 18kt and includes an insurance appraisal of $450.00.