A Natural Australian Opal Doublet Pendant Sterling SIlver (Stamped 925) Doublet Opal Pendant. Genuine Natural Australian Opal Type 3. Gem Doublet Opal is a hydrated amorphous form of silica SiO2�nH2O consisting of spheres of silicon dioxide molecules arranged in regular, closely packed planes backed by Boulder Opal ironstone (found in remote areas in Queensland Australia). The two layers are bonded with a silica-based adherent which has the same coefficient of expansion as the layers allowing consistant expansion and contraction which keeps the Opal layers free from delamination when coming in contact with water. Guaranteed free of dyes and artificial colour. Doublet Opal is categorised as Natural Opal Type 3.All Australian Opal Cutters Jewellery and Loose Opal items are covered by our international warranty. Please send us an note when you check out if you would like to add any modifications or changes or have a specific colour requirement for your Opal. On request and at an additional charge we are able to change or upgrade your Opal (or change the design) of any item that we offer. The item shown online may not exactly reflect the item you recieve as Opals have a living play of colour that can be difficlut to capture on camera.