Show them the green! There are at least seven green gems that should fit the bill-and pocketbook-this holiday season. From the rare to the familiar, they include emerald, chrome diopside, chrome green and green tourmaline, tsavorite (transparent grossularite) and demantoid (andradite) garnet, and peridot. Yes, there are green diamonds, too. But, just like red diamonds, they’re extremely rare and pricey-in other words, almost impossible to find and afford. One of the latest examples comes from Sotheby’s auction house in New York, where in October 1999, a .90-ct. fancy vivid green round brilliant sold for $600,000-that’s $670,000 per carat.
History and romance. Green is a soothing, natural, healing color, said to represent the spring and the green fields that are so calming and easy on the eyes. Wearing green is supposed to signify childish delight and change, as winter changes into spring. Green symbolizes luck-as with four-leaf clovers-and wealth, the color of money. Green is also one of the colors of the holiday season, identified by the evergreens and pines that stand out amongst bare-limbed trees and white snow.
Color variations. Green can be modified by four neighboring colors: yellow, olive, blue, and gray. In most gems, the pure green color is the more valuable and sought after. For emeralds, however, the Muzo mine in Colombia sets the standard for producing top color. The finest Muzo stones are categorized as a medium-dark, vivid, very slightly bluish-green.
Gems colored green by trace amounts of chromium display a more pure and saturated green than the more common varieties of green gems. Commercial peridot is considered yellowish or olive green rather than a pure green, but some can come close to being a pure green.
Chrome diopsides and tourmalines, as well as tsavorites, are rich, saturated, pure greens. Common green tourmaline, like peridot, is somewhat yellowish. Demantoids actually should be medium in tone and yellowish in color, rather than a dark saturated green (which they can be), since these aspects will help the gem disperse light into spectral colors, a feature that is exclusive to this particular garnet.
Other possibilities. As with red gems, consider offering “collector stones”-gemstones too rare or too fragile to be worn in everyday jewelry. These include non-transparent green gems that are either more ornamental in style or do not occur in a pure green color.
Green beryl, for example, is too light or pale in color to be considered emerald but is a wonderful stone in its own right. Green chrysoberyl can be a nice alternative, but it loses its promotional value by being related to such phenomenal stones as the cat’s-eye and alexandrite. Green sapphire is typically too dark to be popular, but because of its affordability, it has become a staple of home shopping TV networks.
Translucent green gems are another possibility. Among them are green grossularite garnet (a.k.a. “transvaal jade” and “New Zealand green stone”), jadeite, nephrite, and serpentine jades, and the ornamental banded malachite.
Red and green bicolor tourmalines, as well as andalusite and alexandrite, can offer the best of both worlds-two colors in one gem. Bicolored tourmalines get their colors from different growth zones: One portion of the crystal grows green, the other portion grows red. Andalusite, on the other hand, gets its color from pleochroism, an optical property whereby a gem displays different colors when viewed from different directions. Andalusites are generally cut so that the green color is seen face-up through the table area, and the red color is seen looking through the ends of the stone. However, because the crown facets are angled, one can see some of the ends’ red color while the gem is still face-up.
Alexandrite, the most impressive-and expensive-of the three gems, shows its red and green under different lighting environments. The gem appears green under daylight or daylight-equivalent fluorescent lighting and red under candle or incandescent lighting.
Value. With the exception of emeralds, all of the transparent green gems noted above should be relatively free of eye-visible inclusions. But, as with red gems, clarity is less important than color.
When examining a gem for color, realize that there is inherent color (the color that truly exists within the gem) and apparent color (the color of the gem when viewed in the face-up position). Cutting a gem to release its color face-up is the “art” in the fine art of stonecutting. Many lapidary artists can enhance the face-up appearance by paying close attention to the angles, polish, and symmetry of the facets. Color is important, but face-up color-dependent on the expertise of the cutter-makes a gem valuable.
The latest prices. Good-quality 1-ct. green gems come in all price categories. Emerald prices range from $600 to $800 per carat, whereas chrome diopside is a very affordable $40 to $60 per carat. Chrome tourmalines are pricier at $150 to $200 per carat, with the common green tourmaline averaging approximately $40 per carat. (Bluish-green Paraíba tourmalines are very pricey-$2,000 to $3,000 per carat.) Green grossularite (tsavorite) from Kenya and Tanzania costs between $350 to $450 per carat; demantoid (andradite) garnet is priced slightly higher at $400 to $700 per carat. Peridot, the birthstone for August, is the most affordable of the green transparent gems, selling for roughly $15 to $25 per carat.
Enhancements. Emerald fissures can be filled, as can tourmaline fissures. Any green diamond should be suspected of having been irradiated to achieve its color. Natural green diamonds also get their color through irradiation, but in the ground. Therefore, green diamonds are extremely difficult to identify as natural or enhanced. None of the other transparent green gems listed here have any enhancements-their colors are natural.
Recommended reading. For more information on green gems, see the following:
Handbook of Gem Identification by Richard T. Liddicoat (GIA, 1990).
“Russian Demantoid” by W.R. Phillips and A.S. Talantsev, Gems & Gemology, Summer 1996, p. 100.
The Curious Lore of Precious Stones by George Frederick Kunz (DoverPublications, 1971).