October Birthstones

October Birthstones


Tourmaline is one of two birthstones for October (the other October birthstone is opal). Very few gems match tourmaline’s dazzling array of colors. Among the most popular colors are the pink, green, bi-color and watermelon. 

  • Rubellites are tourmalines with reasonably saturated dark pink to red colors and medium to dark tones.
  • Indicolite is dark violetish blue, blue, or greenish blue tourmaline.
  • Paraíba is an intense violetish blue, greenish blue, or blue tourmaline from the state of Paraíba, Brazil. This mine is closed and the term "paraiba" now often refers to color rather than where tourmaline was mined.
  • Chrome tourmaline is intense green. In spite of its name, it’s colored mostly by vanadium, the same element that colors many Brazilian and African emeralds.
  • Bi-colored tourmaline displays more than one color. The most common combination is green and pink, but many others are possible.
  • Watermelon tourmaline is pink in the center and green around the outside. Crystals of this material are typically cut in slices to display this special arrangement. 

The most important and plentiful source of tourmaline is Brazil. For the widest variety of color choices and good saturation, Brazilian tourmaline is an excellent choice.

Maine tourmaline is available in limited quantities and is Maine state's stone. Maine’s first major tourmaline deposit was discovered in 1820 at Mount Mica in Paris, by two young boys exploring the local area. Mount Mica intermittently produces various colors of gem tourmaline. The Dunton mine, near Plumbago Mountain, is the most prolific producer of tourmaline in Maine. Prices for Maine tourmaline are generally higher per carat than Brazilian tourmaline. Some beautiful Maine tourmaline colors include apple or mint green and pastel pinks.

Tourmaline is rated 7 to 7.5 on the Mohs scale of hardness and is generally suitable for everyday wear.


Opal is one of two birthstones for October (along with tourmaline). Most opals are valued for their shifting colors in rainbow hues which is known as a “play-of-color" when an opal is viewed from different angles. This flash of color or fire is caused by diffraction when light travels through tiny silicate spheres and edges within the opal. Like a prism, the opal splits the white light into all the colors of the spectrum resulting in an eyeful of beautiful opal. Since the interior structure of each opal is different, each opal is unique and individual. No two opals are alike. 

Although opals are found in many places around the world, Australia is the most productive source for opals.  Australian black opals are mostly mined in Lightning Ridge, in northern New South Wales. Black opal has a dark body tone which can range from dark grey to jet black. Because of their dark body tone, the rainbow colors in a black opal stand out distinctly. 

Boulder opals are found only in the state of Queensland, Australia. Boulder opals are easily distinguished by their layer of solid brown ironstone left on the back of the stone. These opals are mined from large ironstone boulders under the ground. Due to the dark backing provided by the ironstone, boulder opals generally have a dark body tone which leads to a vibrancy of color similar to that found in black opals. Boulder opals are almost always cut in a free form shape.

White opal is found in the White Cliffs area of New South Wales, as well as in Mintabie, Andamooka and Coober Pedy in South Australia. Ethopia is a source of many different color opals as well as the crystal opal. The term “crystal opal” refers to any kind of opal which has a transparent, translucent, or semi-translucent body. where light is able to pass through the stone, or you can see through an opal.

Mexican fire opals are translucent to transparent with a yellow, orange, or red body color. The “fire” in their name refers to their body color, not to play of color. These stones are also called sun opals.

Opals have a hardness of 5 to 6.5 on the Moh's scale and can be scratched by other gems. Since opal is a soft stone, approximately the same hardness as glass, it is important to treat your opal carefully in order to avoid damaging it. 

Opals are often stabilized to make them more durable and wearable. Gem cutters can take opal pieces too thin to use as a solid gemstones and assemble them into doublets and triplets. A doublet consists of a thin layer of precious opal glued to a black base. A triplet adds a transparent, quartz cap. Triplets make good ring stones because the hard quartz keeps the softer opal from scratching. Opal may be treated by impregnation with oil, wax or plastic.