Garnet Buying Guide
With so many color options and a wide range of prices, choosing a garnet can be daunting. In fact, the term “garnet” covers a large group of minerals on a spectrum of chemical composition. Available in nearly every color, the January birthstone can fit into any wardrobe. Its common varieties are affordable, and the rarer specimens within the garnet group are a thrill for collectors. Since prices depend on nuances in color and chemistry, understanding the quality factors for this gem is essential for your next garnet buying trip.
Garnet Varieties and Blends
First, the species or variety of garnet can impact price and the gem’s use in jewelry. In reality, a stone is a blend of the end-member chemistry. However, these terms will help you understand why some garnets are much more valuable than others. Learn to identify the different species of garnet.
The IGS garnet value listing has price guidelines for each gem-quality variety of garnet, as well as cat’s eye and star garnets.
Almandine is the most common garnet gemstone. In fact, the deep red color coveted in garnets usually represents a mixture of almandine and pyrope. Available in standard sizes and a wide range of red hues, almandine gems are less expensive than their rarer cousins. They also possess a hardness of 7-7.5. While this variety sometimes occurs in large sizes, larger stones are often too dark to be gem quality. Faceted gems are generally eye clean.
With high dispersion and limited deposits, andradites are the most highly sought garnet species. While this variety has a lower hardness, 6.5-7, its dispersion exceeds diamond’s. When cut and set, it simply dazzles. Additionally, andradites can have “horsetail” inclusions, a delight for collectors. Three sub-varieties of andradite have been identified: melanite, topazolite, and demantoid. Melanite contains titanium and exhibits a beautiful black color with exceptional shine. Meanwhile, topazolite displays a yellowish-green color, often similar to classic topaz. (However, garnet and topaz comprise different gem species). Topazolite is usually small, and gem-quality specimens are rare.
Perhaps the most valuable variety of garnet, demantoid displays green hues due to its trace chromium content. It also shows the high dispersion that collectors covet. However, often strong secondary yellow hues make the gem less valuable. Thus, for this variety, connoisseurs face a trade-off between color intensity and dispersion visibility. Some prefer deeper greens, while others delight in the bright fire of gems with somewhat lighter tones.
Light to medium in tone and exhibiting almost every color of the rainbow, grossular garnets make fantastic gems. Although their color rarely reaches the deep red commonly associated with garnets, they occur in every color, except blue. Yellow-orange hues are the most common, while yellow-green hues are the rarest. Mint green (Merelani) colors are beautiful and valuable, with large specimens both rare and expensive. First produced as a byproduct of tanzanite mining, Merelani mint garnets only occur in a few areas of the world. Grossular garnets vary in hardness from 6.5 to 7.5, so inquire about hardness before purchasing one. Two popular gem-quality sub-varieties of this gem, hessonite and tsavorite, enjoy frequent jewelry use.
Commonly yellow to orange due to manganese, hessonite has a hardness of 6.5, lower than most other garnets. In fact, its name comes from the Greek hesson for “inferior,” due to this quality. Still, this gem can be quite stunning. Bright orange hues attract the highest values. The occasional honey-colored inclusions don’t detract from the gem’s value. Some hessonites have a pinkish hue. The most common of grossular varieties, hessonite can be affordable.
Tsavorites are quite valuable. Although their color rivals emerald green, their eye-clean clarity exceeds all but the very finest emeralds. Tsavorite’s price also rivals demantoid’s, which has higher dispersion but commonly exhibits secondary yellow hues. Tsavorite color arises from the presence of vanadium, sometimes accompanied by chromium. These gems are rare above 1 carat, but small cuts of clean material are common. With a hardness of 7-7.5, these stones surpass demantoids in durability. Thus, they may also make better ring stones.
Mineralogists debate the classification of this massive species. Some consider hydrogrossular garnet a form of grossular. Others deem its chemistry different enough to merit being its own stone. Regardless, this gem stands out from the rest. Although never transparent, hydrogrossular makes beautiful cabbed or carved pieces. Sometimes marketed as “Transvaal jade,” this stone is often blueish green in hue and can serve as imitation jade. Pink, white, and grey stones also occur. (Of course, garnet, jadeite, and nephrite are all distinct minerals).
Pure pyrope is unknown in nature. Most specimens blend with almandine, forming the classic red hues famous in garnets. Some stones also contain spessartine chemistry and exhibit orange hues. Pyrope blends sometimes display phenomenal color change between daylight and incandescent light. Additionally, pyropes are hard (7.0-7.5) but rare in large sizes.
Notably, some gems have trace iron and manganese content, which imparts a bright pink hue. At first, these gems were mistakenly identified as grossular. However, they’re actually “pastel pyropes.” Occasionally, these exhibit a fantastic pink-to-purple color change.
Pyrope with chromium oxide content exhibits a beautiful violet-red hue. Aptly named chrome pyrope, this gem’s color can rival that of ruby. However, most chrome pyrope has a very dark tone, and only small gems are bright enough for faceting.
Rare garnets with significant spessartite content exhibit orange hues. Those with a somewhat reddish hue, arising from almandine components, have the finest color. Lighter orange gems are chemically closer to pure spessartite. Red-brown hues indicate a larger amount of almandine. Often dark but with a hardness of 7.0 to 7.5, spessartites with lighter tones make ideal jewelry stones. In fact, these gems have a very high refractive index (RI). This gives them a spectacular brilliance when properly cut.
Specimens from the Little 3 Mine in California can have especially fine color. Unfortunately, this mine no longer operates. Thus, the price of these garnets can be much higher than African material.
The finest pure orange spessartite garnets are mandarin garnets. With a name that references this stone’s color, these very rare gems are mined in Namibia, Nigeria, and Tanzania.
The rarest of the garnet group, uvarovite of facetable size and quality is almost never found. However, this deep green garnet is essential for a complete collection. Most uvarovite is opaque, and only small quantities are transparent enough for faceting. Even a cut stone of one carat is almost unheard of. However, uvarovite druzy can be spectacular. Some modern jewelers have incorporated sparkling uvarovite druzy in jewelry pieces.
A purplish-red blend of almandine and pyrope, rhodolite has become very popular. Chemically, rhodolite is three parts almandine to seven parts pyrope, and small changes in chemistry can alter the stone’s hue and tone. In fact, gems with trace amounts of iron and magnesium exhibit a deep purple hue, often called “grape garnets.” For these, the top color is a bright purple, and prices drop for stones with greater red hues.
While the original North Carolina source yielded only small stones, recent finds in Africa have yielded larger rhodolites and made this garnet variety more accessible. Notably, fine rhodolites from tanzania may be marketed as “umbalite.” Pricing for rhodolite is fairly affordable, and these gems are hard enough for any jewelry setting.
First known as a pink blend, malaia or malaya garnets occur on a spectrum of colors including pink-orange, yellow-orange, orange, and red. For these gems, tones range from light to dark, and their chemistry can include pyrope, almandine, spessartite, and grossular, with small amounts of andradite. These stones are fairly affordable, but sizes above four carats are rare. In addition, eye-clean material is common, so avoid visible inclusions. With a hardness of 7 to 7.5, these gems are appropriate for any type of jewelry.
Displaying yellow, yellow-green, or yellow-brown hues, Mali garnets are a hybrid of grossular and andradite chemistry. With andradite’s high dispersion, these stones are stunning. As with other garnets, green hues are rare, so stones with green primary hues sell at a premium. Again, brownish-hued specimens are less expensive than yellow or yellow-green gems.
Color Change Garnets
Some garnets change color depending on the lighting. These are generally blends comprised primarily of pyrope and spessartite and can exhibit a wide variety of color changes. Although no blue garnets occur in natural lighting, some appear blue under artificial light. Color change garnets command prices based on the strength of their color change. Therefore, specimens with strong color change can be quite expensive. Unscrupulous dealers may sell color change garnets as alexandrites, a much rarer and more expensive stone.
With such a wide variety in chemistry, not all garnets are gem-quality. Goldmanite, henritermierite, kimzeyite, majorite, schorlomite, and yamatoite are a few of these collector’s specimens.
Garnet Buying and the Four Cs
While each garnet variety has its virtues, garnets share mostly similar quality factors across their chemistry.
Garnets come in all colors of the rainbow, except blue. Colorless stones and beautiful black gems also make up a part of the garnet group. As with other colored gems, color is the most important quality factor.
Overall, red garnets are the least expensive, while rare orange and green gems are pricey. If you’re looking for a particular color, this section of the guide can help you find the garnet family member that best suits your style and budget.
For good reason, most people associate garnets with red. The most common gem-quality garnets exhibit beautiful deep red hues. Generally a mixture of pyrope and almandine, these gems are reasonably priced. Rhodolite and malaia blends can also exhibit enticing reds. However, large red garnets are usually too dark for jewelry. Thus, large specimens that are light enough in tone to exhibit a desirable red will fetch a good price.
Malaia garnets can exhibit lovely pink tones. In fact, orange-pink hues are some of the most splendid of this variety. Hessonite can have a similar orange-pink color at a somewhat lower price. However, hessonite’s softness makes it more susceptible to scratching. Those seeking a deeper color should consider rhodolite or a pastel pyrope, which can have raspberry or hot pink hues. Hydrogrossular can also have pink hues but lacks transparency.
Shades of orange are rare, so good material is highly sought. Spessartites, especially mandarin garnets, exhibit stunning oranges. Some spessartites have orange-red hues, which are considered the top color for this variety. Additionally, spessartite has a high RI, giving it a brilliance rivaled by few gems. Malaia and hessonite garnets are also orange, but at a much lower price. Secondary yellow hues are common in hessonite and create a bright look.
Brown hues are especially common in orange gems. Make sure to view any orange stones under different light sources before purchasing. Material that’s bright orange in daylight often turns brown under artificial lighting.
Grossular, including hessonite, can be yellow. The much rarer topazolite, an andradite variety, can also exhibit yellow hues. Topazolite exhibits very high dispersion but rarely occurs as gem-quality material. As a result, this gem is much more expensive. For a compromise, consider Mali garnets. This blend of grossular and andradite chemistry exhibits andradite’s high dispersion but is much more common than topazolite.
Several varieties of garnet can be green, but all green garnets are rare.
Demantoid garnets have exceptional dispersion. However, secondary yellow hues, usually undesirable in green gems, occur commonly in this variety. Additionally, there is a trade-off between depth of color and intensity of fire. Deeper colors may mask the stone’s fire, while lighter colors allow it to shine.
Tsavorite often exhibits emerald hues, with primary green colors enhanced by 10-15% secondary blue hues. Larger amounts of blue are even more highly prized because few garnets display any blue hue. Similarly, secondary yellow hues detract somewhat from the price.
Some grossular garnets that could be classified as light-toned tsavorites are marketed as Merelani mint garnets. These popular stones have a distinct blueish green hue and are less expensive than their darker counterparts.
Uvarovite is extremely rare and hardly ever large enough to cut. However, the electric green of this gem is exceptional as druzy.
The reddish-purple tones of rhodolite are popular and affordable. This gem ranges from coveted raspberry hues to purplish red and red. Additionally, rhodolite is generally bright, unlike its darker red cousins. “Grape garnets” are rhodolites with deep purple hues. Deeper purple colors are more costly than reddish-purple hues.
© Artinian Gems. Used with permission.
Pastel pyrope, chrome pyrope, and purple grossular also make great options for those seeking a purple garnet.
Black gems usually offer little to talk about. However, melanite, a variety of andradite, is stunning and sophisticated. This gem’s high dispersion makes it a beautiful accent for any wardrobe.
Collectors prize rare, colorless garnets. Such gems are often almost chemically pure garnets. Thus, they lack the trace metals that give other garnets their hues. However, gem-quality colorless stones occur rarely and often contain inclusions.
Color change garnets can exhibit a wide variety of colors and degrees of change. Garnets that exhibit this phenomenon are valued primarily on their intensity of change. A larger shift in hue, for example, from blueish green to violet, has more value than a purple to pink color change.
Garnet clarity expectations do differ with chemical variations. Among the red varieties, eye-clean specimens are abundant. However, orange garnets often contain some inclusions. Andradite garnets, including demantoids, frequently contain horsetail inclusions. Beautiful to observe, they also give the stone a unique character.
Some garnet inclusions will form a cat’s eye or a four or six-ray star. Star garnets are very rare, with India and Idaho the only known sources for such gems. Six-rayed asterism in garnets is rarer than four-rayed asterism. True chatoyancy in garnets is even rarer. In fact, most cat’s eyes are cut from star garnets.
Again, cut expectations vary somewhat between garnet varieties. Common varieties should always receive cuts to maximize performance, while rare specimens may be cut to retain weight. For example, lapidaries may cut andradite garnets to best feature horsetail inclusions, while cutting cleaner stones to showcase this variety’s excellent dispersion.
Tsavorite and demantoid garnets are uncommon in large sizes. As a result, price per carat rises quickly for these varieties. Similarly, uvarovite of facetable size and quality is extremely rare, so its price reflects this scarcity. However, for the more common garnet species, the price per carat doesn’t rise steeply for larger gems.
Garnets vary somewhat in hardness, which affects their suitability for jewelry use. A hardness of 7 can act as a practical threshold for daily wear, since household dust won’t scratch gems of hardness of 7 or higher. Such gems make ideal stones for daily wear jewelry. By the same token, gems with a hardness below 7 are susceptible to scratching. They’re not recommended for rings, bracelets, or cuff links intended for everyday use.
Because the garnet family sits on that threshold, with a hardness range of 6.5 to 7.5, ask your dealer about a stone’s hardness and jewelry care recommendations before purchase.
Garnet enhancements or treatments are very uncommon. Moreover, very few garnets benefit from treatment.
Most red garnets are rich in iron and can acquire a metallic crust after heat treatment. Though most collectors may find this undesirable, some may enjoy gems that combine the metallic sheen of hematite with the inner glow of red garnet. Once marketed as “Proteus garnets,” these are no longer commercially produced.
Demantoid garnets sometimes undergo a low-temperature heat treatment. This treatment lessens brown hues in the stone. It mimics the heating that other demantoid deposits have undergone naturally. Such treatment is undetectable and produces a stable color.
Often, synthetic garnets are used as simulants or imitations for other gemstones. While yttrium aluminum garnet (YAG) is the most common, its low RI makes it a poor substitute for diamond. Gadolinium gallium garnet (GGG) has a higher RI and makes a better diamond simulant. However, it has a high cost. As a result, inexpensive cubic zirconia has largely replaced it. Both YAG and GGG are available in a wide range of colors. You may encounter them as simulants for other colored gemstones.
Some synthetic gemstones are used as garnet simulants. However, this is rare because so many garnets are affordable.
Color change glass can simulate color change garnet. Because of the high price of color change garnet, glass makes an affordable alternative, if it’s disclosed as a simulant.
However, an unscrupulous dealer recently sold color change glass as natural garnet. This specimen appeared to be a water-worn nodule, with a RI and specific gravity within range of natural garnets. Understandably, this material underwent examination by several gemologists. Many concluded that it was, in fact, a natural garnet. Yet, the material wasn’t birefringent. A Raman spectroscopy examination finally revealed its identity as color change glass-ceramic Nanosital®.