This is a natural opal from the Lightning Rige mines in New south Wales, Australia. It is a black opal, which means that the backing stone is of a dark colour, in this case dark grey. The polished front displays bands of strong green fire above the backing stone. The opal is drop-shaped, 1.6cm lomg and 9mm wide at its widest point. It weighs 2.45 carat. A beautiful stone, which could be made into a lovely pendant or could just be kept as a mineral sample.