Birthstones by the Month

One of the October Birthstones is Tourmaline

A cut Gemstone of Tourmaline.

Tourmaline Gemstone

A beautifully cut tourmaline gemstone from the Cruzeiro mine, Southeast Region, Brazil. [4]

Tourmaline Mineral Form

Made from aluminum borate silicate, Tourmaline is an uncommon gemstone for many reasons. Tourmaline has the ability to mimic most other gemstones in color to a high degree.

In fact, many previously gems from antiquity thought to be Rubies are actually Tourmaline. Tourmaline is composed of not one, but multiple chemically unique minerals categorized as Elbaite, Schorl, Dravite and Liddicoatite. Gem-quality Tourmaline is almost always Elbaite.

Tourmaline crystal formations exhibit polarity, which means the gemstone has a different magnetic charge at opposite ends. Due to this natural magnetism, the Tourmaline has been used in more than just jewelry applications, including in the production of pressure sensitive submarine gauges during WWII.

2 Pound Tourmaline Crystal the October birthstone

2 Pound Tourmaline Crystal

This is a very impressive 805 gram (about 2 pounds) specimen from the turn of the 1900's. This piece is a survivor, and a rare one, of those early California tourmaline mining days. [2]

Tourmaline Facts

Tourmaline does not just come in multiple varieties from different places, Tourmaline has the ability to display drastic color differences in the same crystal formation. This multicolored zoning is a result of a change in concentration of varying trace elements during formation. Due to the gemological makeup of Tourmaline, this gemstone can strongly display pleochroism. If a gem has pleochroism, different colors will display at the same time depending on the direction light is hitting the crystal formations.

The characteristics of Tourmaline

Since Tourmaline comes in such a vast array of colors, the individual colors have been given names for easier identification. Red Tourmaline is referred to as rubellite, blue as indicolite, green as verdite, brown as dravite, schorl for the common black variety, achroite for highly rare colorless crystals and paraiba as an uncommon vividly green version. Other names include watermelon, chrome and more. With a decent Mohs hardness of 7 to 7-1/2, Tourmaline is safe to be used in most jewelry applications.

Triangular star of Tourmaline.

Triangular Star from Madagascar

A classic and beautiful polished liddicoatite tourmaline slice from Madagascar. This piece of tourmaline has green a outer rim and a cranberry-red triangular star core.[3]

Cut and Clarity for the October birthstone

Tourmaline can be found in rather large deposits with robust crystal sizes as well as flawless clarity. It is not uncommon, however, to find inclusions in Tourmaline, especially captured liquid since Tourmaline often grows in moisture-rich environments. If the gem-quality Tourmaline displays pleochroism, gem-cutters must be careful to take this into consideration to emphasize the differing colors as much as possible. Low-quality Tourmaline is often turned into cabochons. Some Tourmaline displays a chatoyant cat’s eye effect thanks to parallel inclusions. Gem-cutters are able to capitalize on this effect when cutting into cabochon shapes. Tourmaline has been used throughout history for carving decorative figures since it does not easily crack during shaping. Higher quality Tourmaline is cut into a variety of classical shapes for use in jewelry applications. Typically, gem-cutters favor elongated shapes such as rectangles. It is not uncommon however for commissioned pieces to be cut in unique and Art Deco shapes for visual intrigue.

Tourmaline the October birthstone.

Tourmaline Crystal

Crystal of tourmaline (elbaite) Santa Rosa Mine, Itambacuri, Doce valley, Minas Gerais, Brazil [1]

The value of Tourmaline

Just as varied as the colors of Tourmaline, so is the value. Common colors, even in larger sizes, are worth less than rare colors. The rarest color, and therefore most highly valued, is pink. The pink variety of Tourmaline is actually considered to be rarer than Rubies. If the quality is high enough to be considered facet-quality rough, prices sharply rise.

Is Tourmaline ever treated?

It is not uncommon to find Tourmaline with minute cracks, and therefore has been known to be treated with colorless resins. The coating of resin improves overall appearance as well as the durability of the enhanced stone. Tourmaline’s color can be enhanced through heat treating. Certain varieties become darker while others actually lighten. Tourmaline should not be cleaned in an ultrasonic cleaner, especially if the gem has been enhanced in any way.

Tourmaline rubellite cluster the October birthstone

Tourmaline (Rubellite)

This is a vibrant sparkling cluster of slender gem Jonas rubellite crystals spraying up from matrix one side. On the bottom more robust darker crystals can be seen. The two major crystals on the upper right side are terminated. [5]

More about Tourmaline the October birthstone

Ancient cultures attempted to explain the wide variety of colors in tourmaline. According to Egyptian myth, tourmaline passes over a rainbow on its journey from the center of the Earth, therefore taking on multiple colors along the way. While Tourmaline is a fairly hardy gemstone, it is best to clean jewelry with this gemstone using mild dishwashing detergent and water. Ensure jewelry is completely dry before storing or wearing. It is also recommended to not expose Tourmaline to drastic temperature changes as this may cause the internal structure to fracture.

The American Gem Society's October Birthstone page has more information to help you buy from knowledgeable and skilled jewelers and to help you make the most informed buying decision.

Image Attribution

  1. By Parent Géry (Own work) [CC0] via Wikimedia Commons
  2. Rob Lavinsky, – CC-BY-SA-3.0 [CC BY-SA 3.0], via Wikimedia Commons
  3. Rob Lavinsky, – CC-BY-SA-3.0 [CC BY-SA 3.0], via Wikimedia Commons
  4. By Didier Descouens (Own work) [CC BY-SA 4.0], via Wikimedia Commons
  5. Rob Lavinsky, – CC-BY-SA-3.0 [CC BY-SA 3.0], via Wikimedia Commons