jade, simulants, dyed quartzite, gems

The strand of variegated green-and-white beads shown in figure 6 had been offered for sale as jade in one instance and as aventurine in another. When we examined the 8-mm beads in the New York lab, the refractive index of 1.55 and the structure proved the material to be quartzite that had been selectively dyed by an unknown process. The resulting product is reminiscent of the jadeite called “moss-in-snow” by one Chinese classification. Unlike most dyed jadeite we have tested in the past, these beads did not appear red when examined with the color filter. Also, they did not show the absorption band centered at 650 nm that is typically seen in dyed material when examined with a hand-held spectroscope. Dye in the cracks was readily discernible with magnification and appeared on a cotton swab moistened with acetone that was rubbed on the bead. By coincidence, the strand of 9½- to 10-mm beads shown in figure 7 was submitted at the same time we were photographing the dyed beads mentioned above. These beads also proved to be dyed quartzite, but they were dyed so well that they closely resemble fine chrome green jadeite to the unaided eye. The beads lack the crackled and dyed appearance that is usually obvious in this type of imitation. In fact, even under magnification the resemblance to jadeite persists. However, the refractive index of 1.55 and the evidence of dye seen in the spectroscope proved the true identity.