Rhodolite Garnet

There are five basic gem garnet species: grossularite, pyrope, almandite, spessartite, and andradite. It would certainly make life easy for jewelers and gemologists if each garnet grew solely within its own mineralogical boundaries. But they don’t. Pyrope, for example, can intermix with spessartite, which can blend in with grossularite. Such changes in chemistry can make identifying—and then naming—the garnet variety a real annoyance. Case in point: rhodolite garnet.

The name rhodolite has long been thought to originate from the rhododendron flower, which is abundant in North Carolina where rhodolites were discovered. The color of rhododendrons has been variously described as pale lilac, pink lilac purple, pastel pink, pale lavender-red, lavender pink, raspberry pink, plum, pink-violet, purplish-pink, violet-red, purple-red, and rose-colored, any of which could be used for the colors of garnets sold as rhodolite.

History and romance. Rhodolite was discovered by Rhode Island mineralogist William Earl Hidden, who uncovered numerous gem deposits in North Carolina, including emerald, and, of course, hiddenite, the rare green spodumene. Hidden even has a town named after him—Hiddenite, N.C., where gem-quality emeralds were recently rediscovered.

Hidden, along with mineralogist J. H. Pratt, found alluvial deposits of rhodolite in Macon County, southwest of Hiddenite, in the late 1890s. Rhodolites were picked up from Cowee Creek and from Mason’s Branch, both north of the town of Franklin, the county seat—locally dubbed “gem of the Smokies.” A primary deposit of rhodolite also has been found on nearby Mason Mountain.

Both the gem and the flower take their names from the Greek word rhodon, meaning rose. The word “rhododendron” might have suggested the Greek nomenclature for rhodolite, but in their 1898 paper proposing the gem’s name, Hidden and Pratt discussed only the Greek derivation. Others made the rhododendron connection, including Max Bauer, who in 1905 said the gem was named after “certain roses and rhododendrons.”

North Carolina is no longer an important commercial source for rhodolite. Sri Lanka, Brazil, Zimbabwe, Tanzania, Kenya, Madagascar, and India are the major sources of the gem today.

Color. When most people think of garnets, they picture what we call almandite—a dark brownish-red or purple-red stone. Almandites have been popular since the early to mid 1800s. Another typically dark-red garnet, pyrope, first gained popularity in the late 1800s. Mineralogically, rhodolite is a combination of pyrope and almandite. But the amount of each present in a gem doesn’t determine if it’s called “rhodolite.” Instead, color is the key: The stone should have some purple, or at least be purplish or “rose-colored.” Gemological labs look for a predominance of purple, 50% or more, but the trade will consider the name “rhodolite” for stones with only a slight suggestion of purple in the hue.

Gemologists break down the rhodolite category by more than simply color—they look at refractive index (R.I.). If a purplish garnet overlaps the high end of pyrope (1.72-1.75) and the low end of almandite (1.76-1.81+), most gemologists will label the stone rhodolite (1.74-1.77). Mineralogists, however, will describe rhodolite as a purplish pyrope-almandine (or pyrope-almandite). And just because it’s purple doesn’t mean it’s a rhodolite. Gemologists may identify a purple garnet as purple almandine because of its higher R.I. (1.78+).

Today, names describing colors, not just chemistry and hue, play a key role in the salability of garnets, including rhodolite. Suppliers are carrying pinkish/orangey/reddish garnets with just a hint of purple. They’re in the rhodolite R.I. range, with probably a chemical mix of pyrope and almandine, and have names like “cranberry rhodolite” and “raspberry rhodolite” to enhance their marketability.

“Grape,” a garnet name trademarked by Columbia Gem House in Vancouver, Wash., is sometimes rightfully called rhodolite. But since it can fall into the higher refractive index category of almandine, rather than the lower pyrope-almandine mix, “grape,” without the hyphenated rhodolite, is the preferred name. “Indigo rhodolite” is used to describe a color-change garnet that has a rhodolite-like purplish color in incandescent light. Mineralogically, it could be confusing since it’s been reported as being a pyrope-spessartine mix.

Qualities. You can count on good color and clarity for rhodolite. Higher quality means more saturated color, but what that color is depends on the taste of your client. Size can be an issue, since most garnets are found as small tumbled rough crystals.

Prices. Each garnet species or variety commands different prices. These are for rhodolite only. According to The Guide, 1-ct. to under 3-ct. fine-quality rhodolites range from $18/ct. to $30/ct. For extra-fine quality, prices can reach $60/ct.

Enhancements. Currently, no enhancements are known to affect any of the garnets.

Bench care and cleaning. Some garnets, rhodolite included, can have a little internal structural stress, so bench jewelers should avoid going directly from steam cleaning to a room temperature or cold rinse.

Otherwise, normal precautions should be taken by your staff and by customers when caring for rhodolite. Hardness is 7-7.5, so dust (which has a hardness of approximately 7) should be washed off, not wiped off, since the dust could scratch and dull the polished surface of the stone.

Recommended reading. For more information on rhodolite, see the following: “A Proposed New Classification for Gem-Quality Garnets,” by Vince Manson and Carol Stockton, Gems & Gemology, GIA, Winter 1985; Naming Gem Garnets, by W. Wm. Hanneman, Ph.D., Hanneman Gemological Instruments, 2000; and Gemstones of North America: Volume II, by John Sinkankas, Van Nostrand Reinhold, 1976.