Natural Australian matrix opal from Andamooka area, which is nicely set into 925 sterling silver pendant on silver chain. Opal is about 8 carat (1.6 g), measuring 20x16x3 mm in size. Total pendant weight (opal + setting) is 15 carat (3g). Setting and bail are 925 silver, stamp is located at the back of the setting. 50cm 925 silver chain is included. Treatment: carbonized and resin stabilized. Andamooka is famous for its matrix opals - when opal fills gaps in porous host material. Is getting more and more popular, as it can produce large stones with very bright colors. Australian opal is sedimentary, formed slowly over millions of years. It's is not affected by contact with liquids, is stable and can last forever if takes care of.