This is a blue opal from Lightning Ridge, New South Wales. It is not really of gemstone quality, because there are no flashes or sparkles, just differet shades of blue. It would certanily make a nice piece for collectors, but alternatively it could still be made into an attractive pendant. The unusual thing about this stone is its relative large size. The sides are 2.2cm long, he base is 2cm long and the top is 8mm long. It is 5mm high at its highest point, sloping gradually towards the top and the bottom. It weighs 17.6 carat. The top has been polished, the back has been left in its natural state.