Natural solid Australian boulder opal from Yowah area, cut and polished to show it's natural beauty with 925 sterling silver bail. Dimensions: 27x20x6 mm without a bail. Opal colors: blue and purple, with some green shades as well present. Play of color depends on lights condition, pictures are made indoors with artificial light. Untreated, just straight from the ground to finished piece of jewelry. 50cm strap is included, so you can wear it right away. Australian opal is a sedimentary variety which is stable, is not affected by contract with any liquids and can last very long time if is used with care. Opal itself is relatively soft stone, but ironstone host rock gives it extra strength and protection. Still try to not weird it to gym or when doing hard labor - to prevent scratches.