Tourmaline – October Birthstone

If garnets and sapphires naturally come in every color of the rainbow, it may be said that tourmaline naturally comes in almost every shade of every color of the rainbow. Outside of possibly fluorite, which is not the best choice for setting in jewelry, tourmaline is the single most colorful mineral on the planet when comes to solid body colors. It’s a veritable paint section at your local hardware store, if you will.

What color are you looking for? Hot pink? Done. Caribbean blue? Done. Peach tea? Done. Hunter green? Canary yellow? Done. Bright green, dark pink and colorless all in the same gem? Done, done, done. The only true limitations you might run into are pure red and pure orange with no modifying undertones, although that’s not to say they don’t exist. They are just very, very rare.

Tourmaline is actually a vast and complex family of silicate minerals. The most commonly encountered gem-grade variety of tourmaline is called elbaite, the lithium-rich member. Tourmaline has pretty good physical properties: it is of reasonable hardness; it isn’t particularly sensitive to chemical attack; and apart from sensitivity to extreme heat, it’s a very durable mineral that shows only poor cleavage.

That all translates into a gemstone that’s suitable for setting in all kinds of jewelry, including rings and bracelets. With the variety of colors available, I’d venture to say you’d be hard-pressed to find a tourmaline that does not appeal to you. There is a tourmaline perfect for every season, to compliment any skin tone, and to round out any wardrobe.

There is a broad swath of trade names you might run across while shopping for tourmaline, including, but not limited to: achroite (colorless), indicolite (blue), rubellite (red with pink undertone and no modifying brown), verdelite (non-chromian green), cuprian tourmaline (blue, green, or purple tourmaline colored specifically by copper), and chrome tourmaline (usually green dravite, colored by chromium). Incidentally, the most common gem-grade color is pink, which is the official alternate birthstone of October to opal.

Apart from its battery of colors, one of tourmaline’s most interesting qualities is its marked pleochroism. Like gems such as tanzanite and andalusite, when you view tourmaline from different angles, you can see different body colors. Some tourmaline crystals have such a dark viewing angle that they appear black. This has led to the creation of what is known as the “tourmaline cut” in lapidary. Crystals with an especially dark viewing direction are cut in a long rectangle with the pavilion so steep as to eliminate any light returning from the dark direction. Other tourmalines show two different shades of the same hue, and they are cut to take advantage of the strongest, purest color so that it is supplemented by the modifying tone.

Other members of the tourmaline group produce gemmy material, as well. Dravite is typically brown to black because of its high iron content, but it does occur in several other colors. Dravite is also the most common variety of tourmaline to be colored by chromium, producing the emerald green coloration of chrome tourmaline.

Liddicoatite is another variety, and it displays just as wide a range of colors as elbaite. Additionally, liddicoatite is usually banded or zoned, so you’re likely to get lots of different colors in the same crystal.

Schorl is very dark bluish or very dark greenish black, which is due, like dravite, to its iron content. But unlike dravite, schorl is almost exclusively so dark as to be opaque. Specialty shops may possibly carry some of these varieties, but don’t expect to walk into most jewelry stores and see them on display.

Caring for your tourmaline jewelry is fairly easy. While extended periods in the ultrasonic cleaner should usually be avoided, steam cleaning low down from the nozzle is generally safe. Tourmaline doesn’t require any special storage like softer gems, and it is stable in sunlight, so don’t be afraid to wear it all day, every day.

Posted in: October Birthstone, Tourmaline

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