The Chinese were expert craftspersons, adept at cutting, boring and polishing Jade and other semiprecious stones using what are believed to be some of the first rotary carving tools in existence. Many different minerals have been called "jade," including what we'd term jadeite, various serpentines, as well as the nephrite we know as "hetian jade." Glass was also a favorite material -- its hardness and the ability of a skilled craftsperson to make it appear to be any of a number of other stones lent itself to the fashioning of many fine works of art. One must remember that glass was in effect a rare and precious stone at the time, to be afforded the same level of respect and invested with the same level of craftsmanship. We also on occasion will sell agate, carnelian or tourmaline pieces, but the bulk of the collection is beautiful hetian jade mined and worked in antiquity in China.
In the above photo you can see some of these materials arrayed - we have jadeite from Burma in the upper-left hand corner, the sometimes high-contrast nature of the mottling apparent. In the upper right we have a serpentine piece, quite a bit more transparent, with a loose network of inclusions, possessing a nice, oily finish. In the lower right is a glass piece, noticeable first due to the damage that has chipped off in a tell-tale conchoidal pattern -- damage to tougher jade pieces tends to be much rougher. Finally, in the lower left corner we have a nearly pure white hetian jade, with milky inclusions and a beautiful softly glossy surface lustre.
At Kojima Jade, we endeavor to ascertain to the best of our abilities the true composition and character of our pieces, examining them carefully and under magnification, and where feasible applying a test of the specific gravity of the pieces.