gems, lapis lazuli, Afghanistan, dyed lapis lazuli, wax treated lapis lazuli

The laboratory is frequently asked to determine whether lapis lazuli items have been treated, with the most common evidence being blue dye visible in fractures or porous zones. Another, less commonly encountered treatment is a surface wax coating, historically used to mask dye or improve the stone’s appearance. Dying is typically done to enhance whitish areas, while waxing can prevent dye from rubbing off or hide poor polishing. A recent case involved a lapis lazuli round-bead necklace submitted to the Los Angeles lab, which displayed an uneven distribution of intense blue and purple hues—suggesting dye. Initial acetone swab testing, however, failed to lift any blue color under normal pressure, though vigorous rubbing produced a faint stain. Microscopic inspection revealed a patchy wax coating, especially where calcite and pyrite were exposed. The wax, easily lifted with a probe, had acted as a barrier to dye detection. Once removed, reapplication of the acetone swab confirmed the presence of dye beneath.