In December 2000, the East Coast lab received for identification a translucent bangle bracelet that was a mottled lavender, green, and orange. It measured approximately 74.75 × 14.20 × 8.20 mm (see figure). Carved from a single piece of gem material, such bracelets are commonly made of jadeite or nephrite, since their exceptional toughness is required to give the piece durability.

Standard gemological testing revealed a spot refractive index of 1.54 on the crystalline aggregate material. This did not match the R.I. of either jadeite (1.66) or nephrite (1.61). Microscopic examination of each color region revealed dye concentrations in fractures and in between individual grains; the dye concentrations overlapped in those areas where two colors appeared to meet. Although we did not see any distinct lines with a desk-model prism spectroscope, the green area revealed a dark absorption in the far red (680–700 nm). The lavender areas fluoresced a medium pink to long-wave UV radiation, and the whole bracelet fluoresced a medium-strong bluish white to short-wave UV. Testing with a Fourier-transform infrared spectrometer (FTIR) confirmed that the bracelet was not jadeite and suggested quartz. More importantly, this spectrum indicated that the bracelet had been polymer impregnated.

Identification of the bracelet as dyed quartzite was not surprising, since this metamorphic rock—formed by the silica cementation of quartz grains—is one of the most familiar jadeite simulants in today’s market (see, e.g., R. Kammerling et al., "Some common—and not so common—imitations of jade," Journal of the Gemmological Association of Hong Kong, Vol. 18, 1995, pp. 12–19). Quartzite is also commonly dyed a variety of colors to imitate various types of jadeite (see Summer 1991 Gem News, p. 122; Winter 1987 Lab Notes, p. 234; and Summer 1987 Lab Notes, pp. 106–107).

What was somewhat surprising was that the bracelet had been polymer impregnated. Jadeite is often "bleached" with acids to remove staining, a process that weakens its structure by dissolving and removing random grains. As a result, bleached jadeite is usually impregnated with polymers to restore durability and improve luster. Such an impregnation may also add color if a dye has been mixed into the polymer. Quartzite should not need to be impregnated, even after "bleaching," because quartz is not soluble in the acids used for jade bleaching. In the case of this bracelet, the impregnation may have been merely a way to carry the dye into the quartzite. Alternatively, the piece may have been polymer impregnated precisely to deceive—not only the casual observer, but also the advanced gemological tester—by giving a polymer signal on the spectrometer. Because there are only slight distinctions in the infrared spectra of jadeite and quartz, a tester who was looking only for evidence of treatment might overlook the subtle differences. Although we reported on an impregnated dyed green quartzite cabochon in the Summer 1995 Lab Notes (pp. 125–126), this was the first tri-colored dyed and impregnated quartzite bangle examined in our lab.