Jade: Jadeite and Nephrite

Jade is the name for two different minerals: jadeite and nephrite. Both are tough, fine-grained rocks made of interlocking crystals, and both have been carved for thousands of years. Jadeite is rarer and includes the bright "imperial" green that commands the highest prices, with Myanmar as the main source of fine material. Nephrite is the jade of ancient China and of Maori carving in New Zealand. Buyers should understand the A, B and C system, which describes whether jadeite has been bleached, impregnated or dyed.

Two minerals called jade

For most of history, people did not know that "jade" covered two minerals. In 1863 the French mineralogist Alexis Damour showed that some jade objects were a pyroxene (now called jadeite) and others an amphibole (nephrite). Both are now accepted as jade.

Neither mineral is very hard, but both are extremely tough. Their tangled crystals or fibers resist breaking, which is why jade can be carved into thin, delicate forms. Nephrite is among the toughest natural gem materials. The page on gemstone durability explains the difference between hardness and toughness.

Both form in metamorphic rocks. Jadeite forms at high pressure and fairly low temperature, often in zones where one tectonic plate dives beneath another. Nephrite forms where magnesium-rich rocks meet other rocks under heat and fluid activity.

Jadeite

Burmese jadeite

Northern Myanmar, around Hpakant in Kachin State, is the main source of gem jadeite. Large-scale trade to China grew in the 18th century, and Qing dynasty court workshops embraced the bright green material. Our page on Chinese imperial jade covers that history. Guatemala supplied jadeite to the Olmec and Maya, described on pre-Columbian jewelry. Japan and Russia also produce some.

How jadeite is graded

No single international grading standard exists, but the trade judges jadeite on a few factors.

• Color is the biggest factor. The top is "imperial jade," a pure, intense, even emerald-green. Other prized colors include apple green, lavender and, in some markets, vivid yellow and red.
• Translucency matters almost as much. The best jadeite is semi-transparent, so light seems to glow inside it. Dealers call this "water."
• Texture describes grain size. Fine-grained jadeite polishes to a glassy surface and looks more translucent.
• Evenness and clarity count. Color should be even, without dark spots, cracks or white patches.
• Cut and workmanship matter for carvings and cabochons. Bangles, beads and high domed cabochons from a single piece of top material are especially costly.

Fine imperial jadeite has sold for very high prices at auction, but most jadeite is ordinary and moderately priced.

Nephrite

Nephrite was the jade of China for most of its history. Neolithic cultures such as Liangzhu carved it into ritual disks (bi) and tubes (cong) more than 4,000 years ago. Khotan, in what is now Xinjiang, was a famous source, especially for pale "mutton fat" white nephrite.

In New Zealand, Maori carve nephrite called pounamu or greenstone into tools, weapons and ornaments such as hei-tiki pendants. Much pounamu comes from the South Island's west coast, and Ngai Tahu holds rights to it under New Zealand law.

British Columbia in Canada is a major producer of spinach-green nephrite, often with black dots of chromite. Wyoming, Russia (Siberia), Australia and Taiwan also produce nephrite.

Nephrite is usually less costly than jadeite. Fine white Chinese nephrite and old carvings can be very expensive.

A, B and C jade

These letters describe treatment of jadeite. They come from the jade trade, not from a formal standard, but labs and dealers use them widely.

• Type A jade is natural jadeite. It may be cleaned with mild acid and waxed on the surface, which is accepted as normal finishing. The color is natural.
• Type B jade has been bleached with strong acid to remove brown or gray stains, then impregnated with polymer resin to fill the weakened structure. The color looks cleaner and the stone more translucent, but the resin can yellow and the stone becomes more fragile over time.
• Type C jade has been dyed, usually green or lavender. Dye can fade.
• B+C jade has been bleached, impregnated and dyed.

Labs detect B jade with infrared spectroscopy (FTIR), which picks up the polymer, and dye with a spectroscope or under magnification. Our overview of gemstone treatments and our guide to gemological instruments explain these methods. Buyers of costly jadeite should insist on a lab report confirming Type A.

Jade imitations

Many green stones are sold as "jade." Common ones are green aventurine ("Indian jade"), serpentine ("new jade"), dyed quartzite ("Malaysia jade"), green grossular garnet ("Transvaal jade"), chrysoprase, prehnite and glass. The page on aventurine covers one frequent substitute. Specific gravity and refractive index separate most of them quickly.

Caring for jade

Jade's toughness lets it survive daily wear, though a hard knock can still crack it. Clean it with lukewarm soapy water and a soft cloth. Avoid ultrasonic and steam cleaning, especially for B or C jade, since heat and vibration can damage resin and dye. Keep treated jade away from solvents and strong heat.

Frequently asked questions

What is the difference between jadeite and nephrite?

Jadeite is a pyroxene with a grainy texture, slightly harder and denser, and includes the rare imperial green. Nephrite is an amphibole with a fibrous texture and is extremely tough.

What is imperial jade?

Imperial jade is jadeite with a pure, intense, even emerald-green color and good translucency. It is the most costly type of jade.

What does Type A jade mean?

Type A jade is natural jadeite that has not been bleached, impregnated with polymer or dyed. Surface waxing is accepted.

Is New Zealand greenstone real jade?

Yes. Pounamu, or New Zealand greenstone, is mostly nephrite jade, though the name also covers related stones like bowenite.