Genuine Australian Triplet Opal 16 x 12 mm Claw Pendant in Stainless Steel. Triplet Opal is classified as Genuine Natural Australian Opal Type 4. It is an assembly of Gem Crystal Opal, a hydrated amorphous form of silica SiO2nH2O consisting of spheres of silicon dioxide molecules arranged in regular, closely packed planes. Backed by Australian Black Opal potch and capped with a cabochon layer of silica quartz. The three layers have the same coefficient of thermal expansion and are guaranteed for life against delamination. Guaranteed free of dyes and artificial colour. Classified by the Opal industry as Natural Opal Type 4 - Triplet Opal is Genuine Natural Australian Gem Crystal Opal, a hydrated amorphous form of silica SiO2nH2O consisting of spheres of silicon dioxide molecules arranged in regular, closely packed planes. Backed by Australian Black Opal potch and capped with a cabochon layer of silica quartz. The three layers have the same coefficient of thermal expansion and are guaranteed for life against delamination. Guaranteed free of dyes and artificial colour.