Jadeite

Jadeite occurs chiefly in serpentine rock derived from olivine-rich rocks, and also as alluvial boulders and pebbles; one rough jadeite boulder from Myanmar weighed 23 metric tons. Myanmar (Burma) is the source of the finest "imperial jade". Other sources include Guatemala, Russia (including fine chromium-rich material from the Kantegir River, West Sayan), San Benito County in California, Japan, Kazakhstan, Mexico, Turkey, France and Italy.

Jadeite and nephrite look alike but can be told apart by testing: jadeite has a higher refractive index (about 1.66 against about 1.61–1.63) and specific gravity (about 3.34 against about 2.95). Jadeite also shows a diagnostic absorption line at 437.5 nm, while deep green material shows a chromium spectrum instead. Some green omphacite has the same gemological properties as jadeite and needs Raman spectroscopy to identify. Jadeite is often treated: "A" jade is untreated (it may only be waxed), "B" jade is bleached and polymer-impregnated, "C" jade is dyed, and "B+C" is both. Lookalikes sold under misleading "jade" names include serpentine ("Korean jade"), aventurine quartz ("Indian jade"), idocrase ("American jade"), hydrogrossular garnet ("Transvaal jade") and dyed marble ("Mexican jade").

With a Mohs hardness of 6.5 to 7 and exceptional toughness, jadeite wears well, even in rings. Untreated jadeite may withstand mechanical cleaning, but acid-treated ("B") jadeite can develop cracks. If the treatment history is unknown, clean it only with warm water, mild detergent and a soft brush, or have it examined by a gemological laboratory.

In Central America the Olmecs, Maya and Aztecs prized jadeite for jewelry, ornaments and religious objects; according to GIA, early Spanish explorers saw people holding it to their sides to relieve pain, and named it piedra de ijada, "stone of the pain in the side", the origin of the word jade. China had worked nephrite for thousands of years; jadeite arrived from Burma (now Myanmar) in the 18th century, and Chinese carvers of the late 18th and early 19th centuries made masterpieces from it. The Chinese called nephrite yu and Burmese jadeite fei-ts'ui, while European traders grouped both as "jade" until Damour separated the two minerals in 1863. Jade is the official gem of the 12th wedding anniversary.

According to GIA, jadeite is regarded as a symbol of prosperity, success and good luck, and the Chinese associate jade with clarity of mind and purity of spirit; Confucius wrote that jade is like virtue. These are cultural associations, not tested properties.

Traditional motifs still carved in jadeite and nephrite carry symbolic meanings in Chinese tradition: the bat symbolizes happiness, the butterfly long life, the dragon power, prosperity and goodness, the peach immortality, and the bi, a flat disk with a hole in the center, heaven.