Tourmaline: Rubellite and Indicolite

Tourmaline has the widest variety of possibilities of any gemstone; it comes in all colors and even two or more colors may be visible in one stone. The chemistry of tourmaline is extraordinarily complex, but nevertheless it is a fairly abundant gem material.

Tourmaline Photo by ICA/Bart Curren

The most common tourmaline colors are greens and pinks. Yellow and violet tourmalines are relatively rare. Tourmaline that falls into the distinctive red colors is called rubellite. Blue colors are called indicolite. Chrome tourmaline is a green variety that is found in Tanzania: in its best qualities it can resemble fine emeralds. Stones with two or more distinctive colors are called bi-color, tri-color or parti-color tourmaline. If the stone is green with pink in concentric bands it is called watermelon tourmaline.

Bicolor Tourmaline, USA Photo by ICA/Bart Curren

You have an infinite number of choices with tourmaline, as well as a wide variety of qualities and prices. Sizes of tourmaline can also vary widely with larger "clean" stones commanding more per carat depending, of course, on color.

Tourmaline, Paraiba, Brazil Photo by ICA/Bart Curren

The highest prices per carat for tourmaline, hitting the expensive range, have been paid for very intense neon-like blue and blue-green colors of tourmaline found in Paraiba, Brazil in l989. Chrome tourmaline, intense blue indicolite, rubellite with a bright red color and no visible inclusions, and flawless bicolor stones will generally run in the moderate price per carat category. Small stones with less intense colors may fall into the low price per carat group.

Valuing tourmaline may be as complex as the group itself. In the tourmaline market over the years supply of one particular type or color will vary, consequently prices may fluctuate greatly depending on supply and demand. Since tourmaline seems to come in an infinite number of colors and combinations, something new may be found in the future which will break the rules.

Tourmaline is available in sizes ranging from very small up to l00 carats or so. Some colors will only be available in smaller sizes. Fine rubellite is not common over 20 carats. Chrome tourmaline is also rare and usually available in smaller sizes.

Multicolored tourmalines Photo by ICA/Bart Curren

Some varieties of tourmaline are more likely to be visibly flawed than others. Bi-color or multi-color stones are usually fairly included. Eye clean multi-color tourmalines with strong color and atttractive variation will command the highest price. Rubellite will also have more inclusions than most other colors. Very clean rubellite with a strong red color is hard to find and commands a price commensurate with its rarity. Much of the rubellite on the market today has been irradiated from lighter pink stones.

Cat's-eye tourmaline is found in variety of colors and is generally semi-translucent to opaque. Look for a strong white eye running the length of the stone. Prices of cat's-eye tourmalines will depend on color, translucency, size and the sharpness of the eye. Some will run in the low price per carat range, but very fine examples will be in the moderate range.

Tourmaline Gemstone Properties

Today there are infinite possibilities of shapes available in tourmaline. Fancy shapes and carved tourmalines can be found. Slightly included tourmaline is perfect for carving. The colors that command the highest prices per carat are usually cut into more conservative emerald cuts, ovals, and cushions.

Tourmaline is dichroic; some are noticeably so. Generally with green tourmaline of medium or darker color, you can observe the dichroic colors by looking down the end of the stone, especially if it is an emerald cut. The color you see on the end may be quite different from the color seen face up. Stones that face up an orangey-peachy color will generally have a yellow color running up one axis and a pink color running down the other axis.

Treatment

Some tourmaline may be heated to lighten it, this is most likely with green tourmalines. Sometimes light pink stones are irradiated and to turn them red. This treatment is not detectable. Heavily included tourmaline may be stabilized with synthetic resins to mask the flaws.

If you are potential tourmaline buyer you will find choosing only one kind or color may be a difficult decision. Of course, you could always start a collection of tourmaline. Who knows what color of tourmaline will be discovered next year?

See Also:

• Gem Dealers's Secrets - Handbook for the Gem Buyer - Table of Content