Fortunoff Fine Jewelry

Gemstone Guide

Gemstones: Nature's Gift

Today, just as in ancient times, people adorn themselves in the many beautiful hues of colored gemstones. Gemstones are usually cut and polished to maximize the play of light and coax luscious color from within. We believe that understanding the methods of fashioning, and the enhancements described within this Guide, will add to your appreciation of the beauty, durability and value of the gemstone jewelry you already own, or purchase in the future.

Regardless of enhancement, all gemstones should be treated with care. Avoid ultrasonic and steam cleaning, and extreme temperatures. Avoid exposure to hairspray, perfume, dry cleaning fluid or other chemicals.

Hundreds of different materials from nature are used to create the lovely adornments we call "jewelry." While we can't list them all, here is a list of the most commonly used gemstones. If there's a gem you love, or want to know more about, that isn't listed here, please contact us for more information.


Treasured by royalty in days gone by, amber is now readily available and quite affordable. This lovely, lightweight gem occurs in shades from pale lemon yellow and butterscotch to deep cherry red and rich dark brown. Amber is usually gently heated to improve its appearance; this does not affect its durability and is permanent.

Amethyst: Purple Variety of Quartz

Amethyst is a member of the quartz family. The medium to- light purple shades of amethyst typically have been heated to enhance their color, while darker hues are not generally enhanced. Amethyst may fade somewhat over the years. More recently, pale purple amethyst (sometimes called Rose de France) has become popular.

Aquamarine: Blue Variety of Beryl

Many aquamarines are greenish-blue when mined and cut. Since the traditionally preferred color of aquamarine is a purer blue, these stones are usually heated to permanently improve their color. Aquamarines are relatively soft gemstones, and care must be taken to avoid chipping or breakage.

Blue Topaz

Nature rarely produces topaz in the blue variety. After the colorless to brownish topaz is mined, it is irradiated to brown and then heated to a rich blue. The various hues are sometimes described by terms such as "London Blue" or "Sky Blue," which refer to the depth and vividness of color. Irradiation levels in jewelry are monitored by U.S. government agencies to ensure complete safety. This enhancement process is stable and requires no special care.

Chalcedony: Microcrystalline Quartz

Used as an ornamental gem for centuries, chalcedony is found in a wide range of colors. Varieties include agate, jasper, carnelian and chrysoprase. The most common, such as black onyx, are typically dyed to achieve uniform color. This is a permanent enhancement.

Citrine: Yellow Variety of Quartz

Pale yellow and brownish varieties of quartz, when heated, generally turn into the bright yellow or orangey colors known as citrine. Recently a wider array of citrine shades have become popular, some with new names, such as lemon citrine and whiskey quartz. The heating that produces citrine is a stable enhancement that requires no special care.


Harvested most frequently from the Mediterranean Sea, Pacific and Indian Oceans, coral occurs naturally in shades from light salmon pink to orangey-red, and more rarely in black and white. Coral is often dyed and/or waxed to achieve more uniform color and luster. This treatment is relatively stable, but is susceptible to damage if exposed to chemicals. Because coral is organic, it is fairly porous and fragile. While coral has been gathered for centuries, environmentalists warn that coral is becoming damaged and may be endangered. For this reason, currently Fortunoff does not carry any coral products.

Cultured Pearl

Today, virtually all pearls are cultured; natural pearls have become extremely rare. Cultured pearls are of three types; the classic saltwater or "Akoya" pearls; freshwater pearls; and pearls from the warmer oceans of the South Seas and French Polynesia (these last are often known as Tahitian pearls). Akoyas are often gently bleached to achieve a more uniform white appearance. They also may be lightly polished to improve their roundness and luster. Our Tahitian and South Sea cultured pearls are natural in color (those sold by other retailers may not be). Many cultured pearls, particularly those from fresh waters, may be dyed or otherwise treated to create more interesting hues. These treatments are all permanent. At Fortunoff, we believe in disclosing this coloring treatment to our customers and include it in our descriptions of these pearls.


Diamonds are treasured for their brilliance and beauty. However, within their crystal structure, there are usually impurities or "inclusions." Over the years enhancement methods such as laser drilling and fracture filling have been developed to improve a diamond's clarity. Fortunoff does not sell clarity-enhanced diamonds. Diamonds may also be color- enhanced, using many different kinds of treatment, from surface coatings to high-pressure, high temperature applications. Some treatments are permanent but others are temporary. At Fortunoff, the only color-enhanced diamonds we sell are black diamonds, which are virtually all color enhanced. Other colored diamonds at are natural color.

Emerald: Green Variety of Beryl

Emeralds have long been prized for their intense green color. When emeralds are mined from the earth, almost all of them exhibit a "jardin"- a garden of inclusions – which distinguishes them as natural gemstones. Traditionally emeralds have had their appearance enhanced by immersion in clear oils or paraffin, which reduce the visibility of the jardin. Today, more sophisticated enhancements are also used. In addition to oils and waxes, clear resins and hardeners may be used to penetrate open fissures. Virtually all emeralds contain at least trace amounts of the oils used on the cutting wheel. Over time emeralds may dry out, requiring light re-oiling to enhance their beauty once again.


Garnets are available in colors ranging from rich red to burgundy, luscious pink to vibrant green, and even golden yellow. This gemstone boasts vivid natural color, excellent clarity and high luster, and requires no enhancement.


Iolite typically occurs in nature in small, deep blue to violet-blue crystals, which are pleiochroic (exhibiting different colors in different directions). Some stones may resemble tanzanite. Iolite is one of the few gemstones that, like garnet, generally is not enhanced. It is a relatively soft gemstone.


Jade actually refers to two mineralogically different materials: nephrite and jadeite. The finest "imperial jade" (jadeite) may have a translucent emerald-green appearance, and is priced on par with top quality ruby, sapphire and emerald. Both types of jade occur most often in shades of green, but also are found in other colors. Jade is graded according to its color origin. "A" jade, the most valuable, is completely natural in color, and the only acceptable enhancement is a light surface coating with beeswax. "B" jade has undergone bleaching and polymer impregnation. "C" jade undergoes the same enhancements as "B" jade, and then is also dyed. Both "B" and "C" jade may become unstable over time if exposed to chemicals, and must be treated with care.

Lapis Lazuli

Lapis is prized for its rich royal blue color, and is valued based on the depth of its color and the quality of the "veins" of calcite, pyrite and other minerals that may run through it. Lapis is occasionally dyed to enhance its color. This dye is stable but is susceptible to damage by chemicals, such as dry cleaning fluid, cologne or hairspray.

Marcasite: Pyrite

This decorative material, fashioned from iron sulfide, is often set into silver jewelry, and faceted or fashioned into beads. Its color may oxidize over time.

Opal: Noncrystalline Quartz

Opals have been prized for centuries for their exceptional play of color. Due to their unusually high water content and noncrystalline structure, opals are susceptible to damage by drying out or cracking. Some opals may be enhanced by heating in a material such as sugar, which shallowly penetrates the stone to artificially color it. Because this treatment may not be stable, Fortunoff does not sell color-enhanced opals. At Fortunoff we search for the harder- to-find natural color white crystal opal, black opal, mosaics or doublets (thin slices of opal affixed to or between other materials). Rare translucent to opaque orange ("Mexican fire opal") and pink shades are also found.


Peridot is found in many locales throughout the world. Typically olive green to bright yellowish green, it does not occur in very large crystals. Peridot is transparent and lustrous. It is one of the few gemstones that undergoes no enhancement.


One of the most abundant minerals, quartz is found in an almost endless variety of colors. These include citrine, rose quartz, amethyst, smoky quartz, chalcedony, and others. The varieties most commonly used in jewelry are discussed individually elsewhere in this Guide; check alphabetically.

Ruby: Red Variety of Corundum

People have long been drawn to the luscious color of rubies, which in nature are rarely a perfect clear red. Most rubies undergo controlled heating to even out their color and reduce the visibility of inclusions. This is routine, and heated rubies require no special care. However, some lesser quality rubies have fissures or surface breaks that may be filled with a glass-like material. This enhancement may not be permanent. Fortunoff will not sell rubies that are fissure-filled.

Sapphire: Varieties of Corundum

Sapphires are available in many hues of blue, from deep midnight to light cornflower. Sapphires also come in a rainbow of colors; pink, orange, green, purple, gold, yellow and white. Few are found in nature with their color fully developed. Controlled heating is routinely applied to most sapphires to improve color and clarity. This enhancement is permanent, requiring no special care. If you are shopping for a sapphire that has not been heated, make sure that it has a report (from a reputable lab) confirming its natural unheated color. Recently, more drastic treatments have been developed, involving chemicals that are "baked into" the stone. These are less stable, and Fortunoff does not carry these "diffusion-treated" sapphires.

Tanzanite: Zoisite

Discovered only in the second half of the 20th century, tanzanite is valued for its exquisite purplish blue hues. Tanzanite is generally heated to change its color from its natural orange-brown to the coveted spectacular violet blue. Extra care must be taken with tanzanite jewelry as it is fragile and easily chipped or damaged.


Tourmalines are found in many colors. Dark blue, blue-green, and green tourmalines are often heated to lighten their color. Reddish and deep pink tourmalines (also known as rubellites) are often heated and/or irradiated to improve their appearance. These enhancements are permanent.


The finest turquoise historically was mined from the Persian Gulf region. While this source has been virtually exhausted, other fine turquoise with a similarly valuable blue color is sourced in the American Southwest. More common green and blue-green turquoise comes from China and other locales. Turquoise is porous; occasionally it is treated with paraffin or similar material to enhance its luster and protect its surface.

If you have questions about how to care for your jewelry, email us at: .

Recently viewed



View Product

Added to cart successfully!