This beautiful boulder opal ring has beautiful shades of blue & green. The stone is set in a fine silver bezel with fine silver back sheet. Ring shank is sterling silver. Because fine silver is 99.9% pure, it is hard to get tarnished compared to sterling silver (92.5%). 【Boulder Opal】 Boulder opal is found only in the state of Queensland, Australia. It is one of the most valuable opals due to its beauty and rarity. I use no doublet/triplet. Ring size: US 5.25 Stone: Boulder opal Shape: Free & natural form Opal size: 16.6 x 9 mm Opal weight: 4.5 carats Metal: Fine silver bezel, fine silver backing, sterling silver ring shank I design and make all of my jewelry in my home studio in Connecticut. 【Customers outside the U.S.】 International customers are subject to customs/duty fees from the post office upon delivery. Especially UK customers, please be aware.