Tortoiseshell is an exquisitely beautiful substance and was popular as a material for vintage glasses for several centuries – tortoiseshell glasses also appeared in later 19th century America. The shell actually comes from the hawksbill sea turtle, and not a tortoise – an unfortunate use for a rare and remarkable creature, though one which, at the time, was held in a strangely intense contempt.
Tortoiseshell glasses frames were made from the earliest times up until the first decade of the 20th century, and only lost their place among the creations of American vintage eyeglasses manufacturers when rubber coated steel frames and plastic coated steel frames were introduced in the First World War era. These substances, especially zylonite, were made to resemble tortoiseshell and were often advertised as such, sparing the innocuous hawksbills any further harvesting.
Genuine tortoiseshell antique eyeglasses are likely to be from the late 19th or the very earliest 20th centuries. If you can positively identify glasses as being made of this substance, then you will have placed the glasses in time fairly accurately. If burnt, tortoiseshell produces a biting, acrid reek not unlike burning hair. This is a drastic form of identification, however, especially for valuable antique eyeglasses, and it is better to pass a finger lightly over the surface to see if it is slickly smooth (plastic or rubber) or if there are slight but perceptible whorls (tortoiseshell).
Tortoiseshell vintage glasses frames can be readily repaired by heating the broken ends and pressing them together, which will cause them to fuse. However, these vintage glasses need to be kept safe from rodents, since mice and rats devour tortoiseshell glasses eagerly, and many old pairs show at least a few nibble marks from the hungry murines of long ago.
Tortoiseshell glasses cases and pince nez cases
Tortoiseshell looks even more spectacular as the main component of a glasses or pince nez case, if possible, than it does as the frames of a set of antique spectacles or Oxfords. The larger surfaces gave the artisan the chance to show off the natural beauty and marbled, variegated hues of the remnants of a hawksbill turtle's shell, rather than just as a bit of striping on the narrow surface of eyerims and temples. These cases are frequently edged with silver, and occasionally with gold.
Tortoiseshell glasses are often best complemented by a period case, though the buyer must beware since better quality plastics have a strong resemblance to tortoiseshell. Their tactile feel is different, however – there are low whorls left by the organic structure of the shell
At least one famous figure associated with American vintage eyeglasses benefited from using a less stylish steel, rather than tortoiseshell, glasses case, however. Theodore “Teddy” Roosevelt was saved from an attempt to shoot him by a saloon owner named John Schrank in Milwaukee. The bullet was slowed enough by the steel case to lodge superficially in the muscle rather than puncturing his lung – a rare instance where choosing tortoiseshell might have been the less optimal decision.