Natural Australian matrix opal from Andamooka area made into 925 sterling pendant with silver bail and silver chain. Opal is 20.5 carat (4.1 g), measuring 25x13x4 mm in size. Has top brightness green sparks with some yellow tints. Blue-purple play of color is also nice. Total pendant weight (opal + setting) is 4.2g. Including chain 5.8g. Bail is 925 silver, stamp is located on the back of bail. 45cm or 50cm 925 silver chain is included. Just let me know what length you prefer. Treatment: carbonized, no coating. 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.