January’s Birthstone and Gemstones: Naming Names for Garnets

You’ll hear a lot of names for garnet gemstones. Firstly, this is because garnets are actually not a single mineral but a group of minerals. They share a similar crystal structure and chemical composition formula, but within that formula, garnets bring in various chemical elements. The proportions of those elements in each particular garnet produces slight differences in optical and physical properties and staggering variety in colors. (Tourmalines and feldspars are also mineral groups. To learn more about mineral groups, I send you to Robert Webster’s Gems: Their Sources, Descriptions and Identification.)

The first name group includes the six species of garnet gemstones recognized by mineralogists: almandite (almandine), pyrope, grossularite, spessartite (spessartine), andradite, and uvarovite. However, garnets rarely belong completely to one of these species. As mentioned before, they collect elements, such as aluminum, chromium, iron, magnesium and others, and mix and match them. The colors and optical properties of an individual stone depend on the percentage of the specific mix of elements in its makeup.

gemstones: hessonite and grossular garnets

Left: As different as possible from the deep green of Tsavorite is this rich red-orange 2.88 carat Hessonite from Baja California. Photo John Bradshaw, courtesy Coast-to-Coast Rarestones International. Right: Grossularite garnets are some of the most versatile of this group, ranging in color from this lovely .95 carat pastel yellow to deep reddish orange. Photo John Bradshaw, courtesy Coast-to-Coast Rarestones International.

That’s not the end of garnet names, though. Mineralogical names–like grossularite–tend to make the eyes of most of us glaze over. So marketers and retailers prefer more romantic names for these gemstones, names that customers can remember and relate to.

That’s how a usually pink to purplish pyrope-almandite garnet came to be known as rhodolite, the color of a rhododendron blossom. Brilliant green Tsavorite is appropriately and exotically named for its source: the Tsavo Valley in Africa. Yellow-orange spessartites may be sold as Mandarin garnets (possibly for their similarity to mandarin oranges). Hessonite, also a type of grossularite, has been known as cinnamon garnet for its warm golden brown color. Tiny spring-leaf-green demantoids (andradite) are found in many antique pieces. Demantoid derives its name from the old German demant, or diamond, because its dispersion (ability to break white light into rainbow colors) is similar to diamond’s.

gemstones: grandite suite and rhodolite garnets

Left: Grandite garnets, faceted by gemstone cutter John Bradshaw, show the color range that a single type of garnet can produce. Grandite is a combination of grossularite and andradite garnet discovered in Mali in 1994. As a result, it is often referred to as Mali Garnet. Photo John Bradshaw, courtesy Coast-to-Coast Rarestones International. Right: Rhodolite garnets, like this .95 carat oval from Tanzania, are favorites of jewelry customers. Rhodolite is a combination of pyrope and almandite. Photo John Bradshaw, courtesy Coast-to-Coast Rarestones International.

Do you need to know all this to enjoy garnets? Good heavens, no! Most people buy garnets by color–gold, orange, red, pink, purple. You just have to remember that garnets are hard, tough, and beautiful gemstones.

Sharon Elaine Thompson is a GG and FGA who has been writing on gemstone and jewelry topics for Lapidary Journal Jewelry Artist since 1987. She also writes a line of Birthstone Romances under the name Liz Hartley.

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