October Birthstones

People who are born in October get to choose between two luscious gemstones as birthstones – Precious Opal and Tourmaline.   Opal and Tourmaline are two of the most beautiful gemstones. Traditionally represented as pink,  tourmaline comes in many colors of the rainbow and a range of shades for each color. Opal is available in a variety of colors, too.

Opal is a hydrated amorphous silica .  Its water content is usually between 6 and 10%. Since opal is amorphous, it is classed as a mineraloid.   Opal is deposited at a relatively low temperature and may occur in almost any kind of rock.   The word Opal comes from the Sanskrit for stone.

There are three types of opal – precious opal, fire opals or Mexican fire opals (generally yellow red), and common opal.   Common opal has little  color play.  Examples are – wax opal, Peruvian opal, or opal agate.  Opal may be transparent, translucent or opaque and the background color may be white or black or almost any color. Black opal is considered to be the rarest, whereas white, gray and green are the most common

Most precious opal is cut and polished as a cabochon. “Solid” opal refers to polished stones that are 100% precious opal. Opals that are too thin to produce a “solid” stone may be layered with other materials:  An opal doublet consists of a relatively thin layer of precious opal, backed by dark material like onyx or obsidian which emphasizes the color play.  An opal triplet is similar to a doublet, but with a domed cap of clear quartz on the top. The dome acts as a protective layer for the opal. The top layer also acts as a magnifier, to emphasize the play of color of the opal beneath.

Beautiful opals require care.  Precious. opal is a softer stone and it contains 3-20% water!  Any loss of water will reduce the amount of color play.  Opal is sensitive to knocks and abrasion and also to heat.

Tourmaline can be opaque or transparent and has a vitreous luster with a hardness of 7-7.5 on the Mohs scale. According to Gemstones of the World, single color crystals are rare – a variety of tones within a single crystal (or even different colors) is more common.  Watermelon tourmaline is one of my favorites and also strands of multicolored stones.

Tourmaline is a crystalline boron-silicate mineral with additional elements such as aluminum, iron, magnesium, sodium, lithium, or potassium. Tourmaline is classified as a semi-precious stone and the gemstone occurs in a wide variety of colors. Tourmaline is actually a group of related varieties rather than a single species. The mineral Elbaite is the member of the Tourmaline group that is responsible for almost all the gem varieties. Tourmaline is the most colorful of all gemstones. Pink, red, green, blue and multicolored are the best known colors. Scientifically, tourmaline is a group of minerals related by physical and chemical properties.

Tourmaline can be opaque or transparent and has a vitreous luster with a hardness of 7-7.5 on the Mohs scale. According to Gemstones of the World, single color crystals are rare – a variety of tones within a single crystal (or even different colors) is more common. The most desirable colors are pink and green. Cat’s eyes are strong only in pink and green hues. Main source of tourmaline is Brazil, but tourmaline deposits are also found in various African and eastern countries. Some deposits also occur in the US.   Heat or pressure can cause a tourmaline crystal to to take an electrical charge that attracts dust and small particles. The result is that tourmaline needs to be cleaned more often than other gemstones. Heating can produce color changes in some stones and may darken or lighten colors, as can irradiation.

If your a looking for alternative October birthstones there are fourteen different stones listed as Sun/Star, Planetary, or Talismanic stones for the Zodiac sign of Libra or Scorpio.  Birthstones for the calendar month of October are opal and tourmaline with alternates of  jasper, aquamarine, coral, and beryl.   The Zodiac signs of Libra and Scorpio include eight additional stones: peridot, sapphire, lapis, agate, topaz, garnet, ruby, and amethyst.