Tortoise Shell vs. Imitations

For thousands of years Tortoise shell has been associated with jewelry and personal items such as combs, eyeglass frames and art objects. They were popular with both the ancient Greeks and wealthy Romans. Many types of tortoise shell objects have been used for furniture inlays, eyeglass frames, decorative boxes, rings, bracelets, and earrings. In Japan, tortoise shell crafting or bekko, has been an important industry since at least the 17th century, centered in Nagasaki. Bekko objects such as hair ornaments are still being created today from stockpiled material. The source material comes from two species of sea turtles: the hawksbill and the rare green turtle. The shell tend to show attractive patterns from light to dark brown patches and other desirable shades. The popularity of tortoise shell from 18th through 20th century caused these animals almost to extinction leading to a near-worldwide ban in the 1970s + international trade in tortoise shell products.

Common imitations include plastic, phenol formaldehyde resin (bakelite), polyester resins (PET and polyurethane) among many others. Sometimes the identification could be a challenge for various reasons. For instance plastics and horn can imitate blond tortoise shell quite easily and the differences in luminescence may not be always diagnostic. Plastic (s) could be altered via change (s) in its chemical compositions, polymerization or the applications of dyes. Identifications may not be always that easy. Since tortoise shell and their imitations are fashioned into ornamental materials, standard tests beyond UV luminescence and hotpoint may not always be possible. It’s catch-22. According to experts, Tortoise shell and its imitations can be identified with standard (microscope, refractive index, specific gravity, UV fluorescence, etc) + analytical (photoluminescence spectroscopy, transmission infrared spectroscopy, specular reflectance infrared spectroscope, vis-nir spectroscope, raman spectroscopy), gemological tests.