verdelite

Verdelite is a historical trade name used to describe green-colored stones within the tourmaline group. It is not a formal mineral species or a distinct mineral, but rather a color variety designation that has appeared in older gem catalogs and some specialty references. In modern gemology, stones with verdélite color are usually described simply as green tourmaline, with the term appearing mainly in older or legacy contexts.

Color and genesis: Verdélite stones range from grassy green to deeper emerald-like greens, sometimes with a bluish undertone. The green color in tourmaline results from trace elements such as chromium, vanadium, and iron. Green tourmalines occur worldwide, with notable sources including pegmatite deposits in Brazil and Africa, among others. The most desirable verdélite specimens display strong saturation, even color distribution, and good clarity.

Physical properties and appearance: Tourmaline, including verdélite varieties, typically has a hardness of about 7 to 7.5 on the Mohs scale and a vitreous luster. Verdélite stones are usually transparent to translucent and are cut into a variety of shapes for jewelry, including faceted stones and cabochons.

Relation to other green stones: Verdélite can be mistaken for emerald or other green gemstones. Gemologists distinguish green tourmaline from emerald by a combination of visual characteristics, refractive index, and, when needed, spectroscopic analysis and mineral identification.

Usage and value: The value of verdélite is driven by color quality, saturation, clarity, and cut. While natural green tourmalines are common in many deposits, high-quality verdélite-like stones with vivid, even color are sought after for jewelry.

See also: Green tourmaline; emerald; peridot.