Dreaming of tourmaline is supposed to insure success through superior knowledge but there seems to be no evidence that the residents of tourmaline mining areas in Maine or California,where such dreams are particularly common,are any better off as a result. John Sinkankas, 1971

A fine chrome tourmaline, a vivid, slightly (five to ten percent) bluish green of about eighty-five percent tone.

Chrome is a special variety of green tourmaline that owes its vivid green hue to trace amounts of chromium and vanadium. These are the same elements that also impart to emerald and tsavorite garnet their distinctive pure green hues. It should not be surprising, therefore, that the finest chrome tourmaline tends to resemble the finer examples of emerald and tsavorite. Chrome tourmaline is actually a distinct tourmaline variety called chrome dravite, found in East Africa. Chrome tourmaline is often associated with tsavorite garnet; miners will usually concentrate their efforts on tsavorite, as it fetches higher prices.

Hue
Like emerald and tsavorite garnet, fine chrome tourmaline is a visually pure “forest” green with slightly yellowish to bluish secondary hues. The blue will normally show itself in incandescent light, the yellow will be more visible in daylight. The same criterion applied to tsavorite garnet and emerald is applicable to chrome tourmaline. A blue secondary hue is preferred to yellow. Chrome tourmaline, unlike emerald, can never be said to be too blue. A visibly pure to slightly (five to fifteen percent) bluish green gem between seventy and seventy-five percent tone is the most desirable.

Saturation and tone
Gray grading to black is the normal saturation modifier or mask found in chrome tourmaline. Due to its chemistry, chrome tourmaline is normally highly saturated. An overabundance of chromium/vanadium appears to be the culprit. A grayish mask is, however, sometimes found. Larger stones tend to be overcolor; that is, so dark in tone as to be virtually opaque. Even though the ideal tone or the gamut limit of green is seventy five percent, chrome of eighty percent tone can be quite beautiful, due to its vivid hue. Stones with tones of eighty-five percent and above are definitely overcolor. Gems of this description will appear to have a virtually opaque black body color punctuated by the occasional flash of vivid green key color.

Multicolor effect
As tourmaline is the most dichroic of gemstones, a strong multicolor effect is to be expected. However, perhaps due to its unique chemical composition and its distinctly dark tone, multicolor effect is rarely observed in the chrome green gemstone.

Crystal
Good crystal is very rare in chrome tourmaline because of its normally dark tone and its behavior in incandescent lighting. Chrome tourmaline, like other members of the species, is a daystone. The stone’s crystal has a tendency to close up — to turn sooty like the chimney of an oil lamp — under incandescent light. It seems particularly sensitive to certain kinds of halogen lighting. If the stone tends toward a gray mask, the yellowish light of the light bulb will also exacerbate that tendency.

Generally speaking, chrome tourmaline is simply more opaque than emerald or tsavorite garnet. Its hue is vivid but it is also dense. A chrome tourmaline that meets the criteria discussed above and that exhibits good crystal — that is, one that retains its transparency in incandescent light — is the crème de la crème of this species.

Clarity
Chrome tourmalines are normally sold eye-flawless. Stones with visible inclusions sell at very substantial discounts.

The rarity factor
Chrome tourmaline is quite rare generally, and particularly rare in sizes over one carat. A stone of fine quality over one carat is very rare. Therefore, the collector should expect a large percentage increase in the price of stones in carat-plus sizes. The next jump in rarity occurs at five carats. Stones of fine quality above ten carats are extremely rare, so rare in fact that I have never seen one.