Only four mineral species can legally be sold as jade: jadeite, nephrite, omphacite, and kosmoclor/maw-sit-sit (the latter two are jadeite mixtures). The finest jadeite is as expensive as any other of the finest gems.
Jadeite comes in a range of natural colors: white, pink, mauve, blue, grey, red, green, lavender, yellow and black, green and lavender being the preferred colors. White jadeite is often dyed green or lavender to raise its retail market value.
In addition to dying, jadeite is often treated with a polymer resin to fill cracks, strengthen the piece, and prevent dye from bleeding when exposed to a solvent.
Cheap beads sold as jade are probably simulants. The most successful natural simulants are some species of the serpentine group, a translucent garnet called hydrogrossular, and some vesuvianite (gem name idocrase). At least 26 minerals are sold as jade (see Identifying Fake Jades). Finally, there is manmade glass treated to look like jadeite.
Jadeite is rarer than nephrite and the main deposits are in North and Central America, Burma, Russia, and Japan.
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