Individuals born in October get to choose between two birthstones—tourmaline and opal. Each gem then unveils nearly limitless possibilities, as each one comes in a rainbow of shades and color combinations.
In fact, both of October’s birthstones came to earth through a journey involving rainbows, according to legend.
Between tourmaline (whose color depends on trace elements in its chemical makeup) and opal (which diffracts light to show a play of multiple colors), October’s birthstones offer a full spectrum of gems to suit anyone’s personal tastes.
HOW TO BUY TOURMALINE
No two tourmaline gems are exactly alike, which makes this a one-of-a-kind gift for any individual—especially someone celebrating an October birthday or an eighth wedding anniversary.
With a wide variety of colors, qualities, and sources available, there’s tourmaline to suit a range of styles and budgets. Like diamonds, tourmaline is evaluated by the criteria of color, clarity, cut and carat weight.
In general, darker toned tourmaline that appears black is priced much lower than brightly colored material. Rubellite tourmaline, in shades of pink or red, is one of this gem’s most desirable colors.
Green and blue tourmaline are also popular, though the most striking shades of these colors come from Brazil’s exotic Paraíba tourmaline. At about $10,000 per carat, this is the most valuable variety of tourmaline.
Some tourmaline material, especially rubellite, undergoes heat treatment to improve color. Another tourmaline is clarity-enhanced to remove inclusions, which can significantly lower the value. Inclusions are common in tourmaline because liquids can get trapped as bubbles during crystallization. It’s not uncommon for red or pink tourmaline to display visible inclusions, but inclusions can drastically lower the value of other colors.
Because of tourmaline forms in slender, columnar crystals, many finished gems have long, irregular shapes.
Tourmalines tend to absorb light down the length of a crystal, rather than across it. This makes these gems “pleochroic,” which means they appear different colors from different directions—so the cut is critical.
Paraíba tourmaline is rare in sizes larger than one carat. But with these stones, color is more highly valued than size, so a small, brightly colored gem is preferred over a large, dark one.
With such a wide range of tourmaline options available—from the common, inexpensive schorl to the highly valued Paraíba—the price of these gems can vary greatly.
The name "tourmaline" comes from the Sinhalese words tura mali, which means "stone of mixed colors." As its name implies, tourmaline stands apart from other gems with its broad spectrum of colors in every shade of the rainbow.
Tourmaline is not one mineral, but a fairly complex group of minerals with different chemical compositions and physical properties. Certain trace elements produce distinct colors, and many resulting varieties have their own names:
- Schorl or black tourmaline is rich in iron, which causes dark shades from deep brown to bluish-black. This variety makes up 95 percent of all tourmaline, though most of it isn’t gem-quality. Schorl, in particular, is said to have protective powers against harmful radiation, toxins, and anxiety.
- Dravite or brown tourmaline is rich in magnesium, which causes colors ranging from brown to yellow. It’s named for the Drave District of Carinthina (now Slovenia) where it’s found.
Elbaite offers the widest range of gem-quality tourmaline colors, due to lithium traces combined with other coloring elements:
- Rubellite or red tourmaline is caused by manganese; but if the color becomes less vibrant under different light sources, it may be called pink tourmaline.
- Indicolite or blue tourmaline can appear purplish blue or bluish green, depending on the amount of iron and titanium.
- Verdelite or green tourmaline can resemble emerald, but if its color is caused by chrome and vanadium, it’s called a chrome tourmaline.
- Paraíba tourmaline is a vividly colored purplish or greenish blue variety found in Paraíba, Brazil. It’s the most recently discovered, and because of its desirable intense colors, it’s one of the most valuable.
- Achroite or colorless tourmaline is rare.
- Parti-colored tourmaline displays more than one color, due to chemical fluctuations during crystallization. A common color combination is green and pink. These are often cut in slices to reveal a red center surrounded by a green rim, earning the name “watermelon tourmaline.”
Tourmaline is desirable because of its sheer range of color options. Combined with a good hardness of 7 to 7.5 on the Mohs scale, tourmaline makes very wearable jewelry.Tourmaline is mined in Brazil, Sri Lanka, Nigeria, Mozambique, Madagascar, Afghanistan, Pakistan and the U.S.—mainly Maine and California.
One of this gem’s most impressive traits is its ability to become electrically charged through heat (pyroelectricity) and through pressure (piezoelectricity). When charged, tourmaline can act as a magnet by oscillating, and by attracting or repelling particles of dust.
Ancient magicians used black tourmaline as a talisman to protect against negative energy and evil forces. Today, many still believe that it can shield against radiation, pollutants, toxins and negative thoughts.