Opal is a hydrated form of silica with a water content which may range from 3 to 21% by weight, but is usually between 6 and 10%. This stone has taken the gem world by storm with it’s amazing color combinations that occur in just one stone. This unique free form Opal is from Brazil unlike most of our material, coming from Ethiopia. It weighs 5.60 cts. and measures 20x9x7 mm.