Jadeite is one of the two species that the trade collectively calls jade (the other being nephrite). It is a sodium-aluminium clinopyroxene of formula NaAlSi₂O₆, in the pyroxene mineral group, and is the source of the imperial-green jade of late-Qing-and-after Chinese tradition, the Olmec and Maya pre-Columbian jade tradition, and the high-end contemporary Asian and international jade market. Jadeite was separated from nephrite as a distinct mineral species in 1863 by the French chemist Alexis Damour, who showed that the recently arrived Burmese imperial "jade" was chemically and structurally different from the historical Chinese nephrite tradition.

Mineralogy and physical properties

Jadeite crystallises in the monoclinic system, space group C2/c, with a Mohs hardness of 6.5 to 7.0 (slightly higher than nephrite), a specific gravity of 3.30 to 3.38 (clearly distinguishable from nephrite's 2.90 to 3.03), and a refractive index of 1.652 to 1.688 with a birefringence of around 0.020 (rarely measurable on a refractometer because of the aggregate texture; the trade reads a single spot near 1.66). The aggregate is microgranular to fine-fibrous, with a characteristic sugary or finely crystalline texture under magnification that is one of the principal field-identification features distinguishing it from the felted-fibrous structure of nephrite.

Pure jadeite is white. The principal colour-causing trace elements are chromium (the imperial green and apple-green), iron (the green-yellow, brown and black variants, and the ordinary commercial green that makes up most of the market), manganese (the rare lavender to violet jadeite of the upper Burmese deposits), and copper (very rare). The full range covers white, all greens, lavender, yellow, orange, brown, red, black and the rare blue-green omphacite-jadeite.

Source localities

The dominant commercial source is the Hpakant region of Kachin State, upper Myanmar, which has supplied the world's only commercial-quality imperial-green jadeite for the past two and a half centuries. The Burmese deposits are alluvial and primary, occurring as boulders weathered from serpentinite-related pods of jadeitite. The Hpakant area mining district covers around 350 square kilometres and supplies essentially all of the high-end jadeite reaching the international market.

Secondary sources include Guatemala (the Motagua valley, source of the Olmec, Maya and Aztec pre-Columbian tradition; modern production exists at small scale), Russia (Polar Urals and Sakha Republic), Kazakhstan, Japan (Itoigawa, the source of the Japanese prehistoric magatama tradition), California (Clear Creek), and Cuba. None of the secondary sources approaches Burma in commercial quantity or in the production of imperial-green colour grade.

Quality factors and grading

The four principal quality factors are colour, translucency, texture and treatment status. Colour is judged on hue (the chromium-driven imperial green is the standard), tone (medium tone is preferred over dark or pale), saturation (high), and distribution (even, without colour banding or veining). Translucency ranges from opaque through the conventional translucent grade to the highly prized "glassy" or bo li zhong grade in which the stone passes light readily. Texture is judged on the fineness of the aggregate grain; the highest grades show no visible structure under ten-power magnification. Treatment status distinguishes A-jade (untreated), B-jade (bleached and polymer-impregnated), C-jade (dye-treated), and B+C jade (both); see the separate Jade bleaching entry. Only A-jade is acceptable in the high-end traditional Chinese trade.

Identification and treatment detection

Jadeite is distinguished from nephrite by specific gravity (a 3.34 hydrostatic reading rules out nephrite at 2.95), refractive index (1.66 spot vs. 1.61 spot), and microscopic texture (sugary granular vs. felted fibrous). It is distinguished from common imitations — omphacite, chrysoprase, dyed quartzite, hydrogrossular garnet, serpentine, glass — by combinations of refractive index, specific gravity and Raman spectroscopy. Treatment detection is by FTIR (showing the polymer C-H bands of B-jade), Raman spectroscopy, long-wave ultraviolet fluorescence (B-jade often shows milky-blue chalky fluorescence), and microscopic examination of the leached granular substrate beneath polymer fill.

Trade and market

The contemporary jadeite market is concentrated in the Greater China region (mainland China, Hong Kong, Taiwan), the Chinese diaspora, and the international auction market through Sotheby's Hong Kong, Christie's Hong Kong, Bonhams Hong Kong and Poly Auction. Major auction prices include the Hutton-Mdivani Necklace ($27.44 million, Sotheby's Hong Kong, April 2014), the Mdivani jadeite cabochon (sold by Christie's Hong Kong, multiple appearances), and various imperial-green bangle and cabochon-bead transactions in the eight-figure range. The market has shown sustained strength since 2000 and is generally treated by the Chinese trade as both a luxury good and a culturally tied store of value.