New Zealand greenstone is divided into several different varieties according to colour: Inanga is highly esteemed, its grey green colour resembling that of whitebait, Kahurangi is a lighter rarer stone, and Kawakawa is dark green, like the tree it is named after.

The greenstone at Milford Tangiwai is not really greenstone at all as it is not nephrite but brownite. However tangiwai has all the mystique of pounamu and highly prized by Maori. It is softer than nephrite so easier to work. It is a very beautiful stone that ranges in colour from a blue-green to an olive-green. The true splendour of tangiwai is only revealed when it has light behind it that illuminate the white speckles that resemble tear drops in the stone. Tangiwai means, “tear water” in Maori.