Nephrite has been used for over 7000 years in China, in carvings and jewellery. Nephrite is tougher than its jadeite counterpart, making it perfect for carvings and objet d’art. It owes its toughness to the interlocking masses of crystals that make up the gem. Nephrite predominantly occurs as dark green to brown, this colour is caused by iron. However nephrite has also been found as orange, bluish grey or black. Black inclusions often occur in nephrite, giving an attractive spotted effect. Deposits of nephrite have been found in New Zealand, Australia, Brazil, China, Canada, Zimbabwe, Russia and Taiwan.