Amazing rainbow colors in this natural Australian matrix opal from Andamooka area, both sides are beautiful. Opal is 15 carat (3 g), measuring 25x19x4 mm in size. Total pendant weight (opal + silver) is 3.25g. Bail is 925 stamped silver. 50(+5)cm black twisted leather strap 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 good colors which would cost a fortune for solid opal. 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.