gems, jade, jade imitations, glass

Imitation jades currently circulating in jewellers market under the name of Syberian jade or Reformed jade were investigated by both non-destructive and destructive methods, with special attention to the inclusions. The imitation jades are made of sophisticatedly produced glass, and are dark green, translucent to opaque with glassy, somewhat greasy, luster, have Mohs' hardness of 5-5.5, sp. gr. 2.67 ± 0.02 at 20℃, refractive index 1.523 ± 0.005, and broad absorption spectrum at 4000-4600Å and 6300-7000Å. They contain characteristic inclusions of the following three types; 1) Needle-like inclusions which are identified to be hydroxyl apatite by optical and X-ray investigations, have hexagonal section, and are uniaxial negative, with no pleochroism, higher refractive index than the matrix. These are grouped into three by their length. 2) Dendrite inclusions with 90° braches are identified to be either vapour or liquid phase inclusions, and have lower refractive index than the matrix. 3) Four other types of inclusions, which are not identified. These imitation jades exhibit psudo-optical anisotropy due to apatite inclusions and are easily identified by their inclusions.