Nephrite is one of the two true jades, alongside jadeite. It is an amphibole rock built from tightly interwoven fibres of actinolite and tremolite, and that felted structure makes it one of the toughest gem materials on Earth. Stone Age people literally made axe heads from it. It has been carved in China for over 7,000 years, where the finest white material is called mutton fat jade, and it is the treasured pounamu of New Zealand's Maori. Other major sources include British Columbia in Canada, Siberia and Australia. Colours run from cream through spinach green to nearly black.
Nephrite sits at 6 to 6.5 for hardness, but its toughness is exceptional. It resists breaking better than almost anything else you can wear, which is why it can be carved into thin bangles and intricate pendants. It is always worked as carvings, cabochons and beads, and it has a lovely soft, greasy polish rather than a glassy one. Care is easy: warm, soapy water. Do watch for dyed material and imitations like serpentine sold as jade; genuine nephrite feels dense, cool and smooth.
Chrysoprase and green aventurine are the most common nephritejade look-alikes, though usually not as dark green.
