Opal & Diamond Ring 14kt Yellow Gold. The month of October’s birthstone is opal….here is a gorgeous ladies ring with opal and diamonds in 14kt yellow gold. This ring is set with ten full cut diamonds weighing 0.15cttw and one oval opal weighing 0.39ct. It is in excellent condition. Ring size: 6 1/2, it is hallmarked: INP; 14k; JP; 696.and includes an insurance appraisal of $894.00.