Boulder opals are natural gemstones typically found in Australia. Frequently cut into freeform or triangular shapes to maximize the opal content. All 3 rings sterling silver 925 and bezel set which provides a secure hold. Rings each weigh 3 grams. Triangular ring size 7.5". Sides are each .50 inches. Teardrop ring size 8". L .50 x W .50. Pear shaped ring size 8. L .50 x W .50. One price for all 3 rings.