The other jade — tougher, less dense, and the material of most historic Chinese and Māori carving.
Myanmar (jadeite), China, Canada, New Zealand, Guatemala (nephrite and jadeite)4 references
Nephrite is a fibrous amphibole, and its dense interlocking fibre structure makes it the toughest natural stone there is — not the hardest, which is a different property, but the most resistant to fracture. That is why it was the working material for axes, adzes and chisels across China, Siberia, Central America and New Zealand for millennia, and why nearly all archaic Chinese jade is nephrite rather than jadeite.
It is softer and lighter than jadeite: 6–6.5 against 6.5–7, and specific gravity 2.90–3.03 against 3.30–3.38. Its polish is characteristically softer too, an oily or waxy sheen rather than jadeite's glassy brightness, and its colour range runs through spinach green, grey-green, black, and the prized creamy white called mutton fat.
For identification purposes nephrite's advantage is that it is much less treated than jadeite. The dyeing and impregnation industry concentrated on jadeite because the price ceiling justified it. Nephrite's problem is simpler: serpentine sold as nephrite, which the specific gravity test catches immediately.
Canadian nephrite · Siberian · Pounamu / greenstone (New Zealand) · Mutton fat white
Establish which of these you are holding before judging it. A genuine piece read against another reference's rules will look wrong when it is not.
These apply to this model and not to the rest of Jade. Work them alongside the maker's general checks, not instead of them.
Nephrite sits in a narrow band that separates it cleanly from serpentine below (2.44–2.62) and jadeite above (3.30–3.38). This is the whole identification and it takes a scale, a thread and a cup of water.
Nephrite's fibrous structure gives a soft, slightly greasy sheen that looks as though the surface has been oiled. Jadeite polishes brighter and more vitreous; serpentine tends to look waxy and slightly soft.
Nephrite at 6–6.5 resists a steel blade everywhere. Serpentine is variable within a single piece and will have somewhere a blade marks. Test several places, not one.
Far below jadeite. Good carving material runs tens to hundreds of dollars; exceptional Siberian and historic Chinese pieces go higher.
An orientation for honest, unrestored condition — never an appraisal, and never a quotation.
Lovenhall StoneThe tests tell you what it is. The instrument reads a photograph and offers a name to start from — then hands you back to the tile and the coin, which are what settle it.