Grossular Garnet Value, Price, and Jewelry Information


merelani mint garnet - grossular garnet
4.20-ct Merelani mint garnet, medium very slightly yellow greenish, cushion brilliant cut, 11 x 7.6 mm, Merelani, Tanzania. No treatments. © The Gem Trader. Used with permission.

Grossular garnets come in almost every color, even colorless, except blue. However, unlike other garnets, they’re rarely red or dark. Often light to medium in tone, they make brilliant, vibrant jewelry stones.

Grossular Value

For information on quality factors for grossular and other garnets, consult our garnet buying guide.

The International Gem Society (IGS) has a list of businesses offering gemstone appraisal services.

Garnet Value via Gem Price Guide
Top Color: oR, R, PR, rP 6/4
AlmandineAll sizes
to /ct
Fine Color Andradite: G 5/4
AndraditeAll sizes
to /ct
Chrome PyropeAll sizes
to /ct
Color Change.5 to 1 carat1 to 6 carats
Africa to /ct to /ct
US to /ct to /ct
Demantoidto 1 carat1 to 3 carats
to /ct to ,000/ct
Grossular Garnet .5 to 1 carat1 to 5 carats5 carats plus
Mint Green (Merelani) to /ct to /ctto /ct
Yellow/Orange to /ctto /ctto /ct
Yellow/Green to /ctto /ctto /ct
Other colors/ct/ct to /ct
Fine Color Hessonite: yO 4/5
Hessonite GarnetAll sizes
to /ct
Malaya Garnet.5 to 1 carat1 to 5 carats5 carats plus
to /ct to /ctto /ct
MozambiqueAll sizes
to /ct
Mali GarnetAll sizes
to /ct
Fine Color Spessartite: O 4/5
Mandarin OrangeAll sizes
to /ct
Fine Color Pyrope: R 6/5
Pyrope1 carat plus
/ct
Fine Color Rhodolite: rP, PR 6/5
Rhodolite.5 to 1 carat1 to 10 carats10 carats plus
Faceted to /ct to /ctto /ct
Cabochons to /ct to /ctto /ct
Spessartite Reds See Mandarin above.5 to 3 carats3 to 6 carats
Little 3 Mine to /ct to /ct
African to /ct to /ct
Darker reds to /ct
Star GarnetAll sizes
6 ray star to /ct
4 ray star to /ct
Fine Color Tsavorite: G 6/5
Tsavorite.5 to 1 carat1 to 2 carats2 carats plus
Faceted to /ct to /ct to ,000/ct
Uvarovite10 carats plus
Druzy to /ct
CabochonsAll Sizes
Common red to purple to /ct

See the entire Gem Price Guide.

Start an IGS Membership today for full access to our price guide (updated monthly).

Grossular Information

DataValue
NameGrossular
Is a Variety ofGarnet
VarietiesHessonite, Hibschite, Hydrogrossular, Transvaal Jade, Tsavorite
Crystallography Isometric.
Refractive Index 1.720-1.800
Colors Colorless (rare), white, gray, yellow, yellowish green, green (various shades: pale apple-green, medium apple-green, emerald green, dark green), brown, pink, orange, orange-red, reddish, black.
Luster Vitreous to resinous.
Fracture Conchoidal
Hardness 6.5 - 7.5
Specific Gravity 3.4-3.71; usually near 3.65.
Birefringence None.
Cleavage None
Dispersion 0.028
Heat SensitivitySome
Luminescence See "Identifying Characteristics" below.
Enhancements Extremely rare: dyeing. Experimentally: irradiation to turn colorless and pale stones yellow-green, unstable.
Transparency Translucent to transparent.
Absorption Spectrum See “Identifying Characteristics” below.
Birthstone January
FormulaCa3Al2Si3O12
Pleochroism None.
Optics  N = 1.72-1.80; usually 1.73-1.76 (with V = 1.743-1.759). May show anomalous birefringence. 
EtymologyAfter the botanical name for gooseberry, Ribes grossularia, since the pale green color of the type specimens resembled that of this fruit.
OccurrenceIn metamorphosed, impure calcareous rocks, especially contact zones; also in schists and serpentines; worldwide occurrence, widespread.
Inclusions Healed fractures (fingerprints), crystals, two phase inclusions, growth lines.
Faceted Grossular - Canada and Tanzania
Grossular Garnet: Asbestos, Quebec, Canada (9.81), Tanzania (4.15, 5.01 // 2.59, 4.48, 2.18, 3.88 // 2.47, 4.82, 4.14). Photo © Joel E. Arem, PhD, FGA. Used with permission.

Comments

Although you might still encounter the term “grossularite,” especially in older reference works, “grossular” is the more commonly used term for this garnet species.

The color of grossulars depends on iron (Fe) and manganese (Mn) content. If a stone has less than 2% Fe, it shows pale colors or no color. Greater amounts of Fe produce brown and green colors. Chromium (Cr) produces a rich green shade. (Tsavorites receive their prized emerald-green color principally from vanadium).

Grossulars have a granular appearance under the microscope, sometimes referred to as treacle. This swirled look comes from inclusions of diopside crystals and irregular streaks at grain boundaries. Some grossulars also have zircon crystal inclusions. Material from Tanzania may have actinolite and apatite inclusions as well.

faceted grossular garnets - Kenya
Tsavorite: Kenya (pear shape, 5.15 // 1.6, 1.4, 0.95, 3.0). Photo © Joel E. Arem, PhD, FGA. Used with permission.

Varieties

The two most well-known gem grossulars are hessonite and tsavorite. For more information on these varieties, consult their individual gem listings.

Like all garnets, grossulars can form series with other garnet species. For example, Mali garnets are a grossular-andradite blend.

Merelani Mint Garnet

Another popular gem grossular, this gem gets its name from its source, Merelani, Tanzania and, of course, its light minty green color.

Leuco Garnet

These colorless grossulars occur in California, Canada, Mexico, Myanmar, and Tanzania. Material from Georgetown, California has N = 1.737 and an SG of 3.506.

leuco grossular garnet - Tanzania
Leuco garnet, fancy brilliant oval, 0.78 cts, 6.83 x 5.21 mm, Tanzania. Rare white color grossular, very slight yellowish tint, no treatments. © Dan Stair Custom Gemstones. Used with permission.

Massive Grossulars

Hydrogrossular can be a component of the massive grossulars. So-called Transvaal jade is the green, massive hydrogrossular material from South Africa. However, not all massive grossulars are hydrogrossular. Pakistan massive grossular has a refractive index N = 1.738-1.742 and a specific gravity (SG) of 3.63, with a Cr absorption spectrum. Similar material from Tanzania has N = 1.742-1.744 and an SG of 3.68.

Californite

A mixture of idocrase (vesuvianite) and grossular garnet. Usually pale to medium green in color, it comes from California, Pakistan, and South Africa.

Rosolite

Also known as xalostocite and landerite, this pinkish grossular in marble comes from Mexico.

grossular cabochon - rosolite
12.93-ct peach grossular, medium-dark slightly orangish pink, round cabochon, 13.4 mm, Mexico. No treatments. © The Gem Trader. Used with permission.

Identifying Characteristics

Almost always zoned and often twinned, grossulars appear distinctly not isotropic under the microscope. Specimens can show anomalous double refraction (ADR) due to strain.

Crystal specimens often show striations.

For information on distinguishing garnet species and blends, consult our article on identifying garnets.

grossular crystal - Quebec
This sherry-color grossular crystal from the Jeffrey Mine in Asbestos, Quebec, Canada shows faces with striations common to these garnets. Dimensions: 2.8 x 2.5 x 1.8 cm. © Rob Lavinsky, www.iRocks.com. Used with permission.

Luminescence

Usually none in ultraviolet light (UV). Some specimens may fluoresce weakly golden yellow under shortwave (SW) or longwave (LW) UV, yellowish green or pink under SW UV, or orangish under LW UV.

All massive material glows orange in X-rays, as do many faceted gems. Yellow grossulars from Tanzania fluoresce orange in X-rays and also UV. (N = 1.734, SG = 3.604).

A very lively green 2.40-ct African grossular garnet with a high polish, under normal light. When placed under UV light, it shows a pink glow. © All That Glitters. Used with permission. (Slide show created to demonstrate the stone’s fluorescence).

Absorption Spectrum

None in pale-colored, faceted gems. A trace of almandine garnet may produce a faint iron spectrum.

A trace of Cr may produce a chrome spectrum in green varieties.

Massive grossular may show a weak line at 4610 or a band at 6300. Green, massive grossular from Pakistan shows a line at 6970 (weak) with weak lines in the orange, plus a strong band at 6300 and diffuse lines at 6050 and 5050.

Orange stones may have bands at 4070 and 4030.

golden yellow grossular garnet - round brilliant cut
Grossular garnet,  fancy round brilliant, 0.88 cts. 5.94 mm, Tanzania. Golden yellow, no treatments. © Dan Stair Custom Gemstones. Used with permission.

Synthetics

Scientists have synthesized grossulars for research into geological history as well as the thermodynamic properties of this garnet. However, there is no known jewelry use of this material.

However, you might encounter simulants, gems that look like grossulars, offered as genuine specimens of the more expensive grossular gems. These may even include lab-created garnets. For example, gemologist and gem dealer Edward Boehm recalls examining a supposed tsavorite, only to find it was a piece of yttrium aluminum garnet (YAG), a synthetic garnet, “fashioned” to appear “fresh from the mine.”

For more information on YAG and other synthetic garnets, see the “Synthetics” section of our main garnet gem listing.

Enhancements

Although garnets have a reputation for typically receiving no treatments, this does occur. As it so happens, grossulars have received some unusual enhancements. In one odd case, a rare colorless grossular was dyed to appear like a ruby. In a 1992 experiment, researchers found that gamma radiation can induce an unstable yellow-green color in colorless and pale hued East African grossulars. In sunlight, the color fades within hours to days. In the dark, within a week. Thus, this process has no commercial viability. However, examining yellow-green grossulars in sunlight is advisable.

For information on additional possible garnet gem treatments, consult the “Enhancements” section of our garnet buying guide.

Sources

Numerous localities produce gem-quality grossulars around the world. Some notable sources include

  • United States: California (many localities); New England region (many localities); Eden Mills, Vermont (fine orange crystals, some gemmy, with green diopside); Washington.
inter-grown grossular garnets - Vermont
Inter-grown, deep amber-color grossular garnets on a bed of diopside crystals. Eden Mills, Lamoille County, Vermont, USA, 2.0 x 1.8 x 1.8 cm. © Rob Lavinsky, www.iRocks.com. Used with permission.
  • Asbestos, Quebec, Canada: fine orange to pinkish crystals at the Jeffrey Mine, up to 2 inches across, gemmy. Also colorless (N = 1.733). (Note: the Jeffrey Mine closed in 2003).
  • Mexico: large pinkish, white, and greenish crystals, color zoned concentrically, usually opaque; crystals up to about 5 inches in diameter. (Note: According to Rock Currier, no garnets come from Lake Jaco, Chihuahua. Rather, the actual source of any gems from said location is Sierra de la Cruz, Mun. de Sierra Mojada, Coahuila, Mexico).
  • Sri Lanka: grossulars (hessonite) found in the gem gravels.
  • Australia: Harts Range, Northern Territory (hessonite).
  • Kenya and Tanzania: fine grossular in various colors (especially tsavorite). Tanzania also produces merelani mint garnets.
  • Wilui River, Russia: opaque green crystals with idocrase. These gems are also known as viluite.
  • China: crystals and massive white grossular.
  • Pakistan: some faceted green gems, also massive green grossular, also various shades.
  • Brazil; Italy; Myanmar; South Africa; Switzerland.
grossular crystal cluster - China
A cluster of golden yellow grossular garnet crystals. Handan Prefecture, Hebei Province, China, 4.2 x 3.7 x 3.3 cm. © Rob Lavinsky, www.iRocks.com. Used with permission.

Stone Sizes

Lapidaries cut massive grossular varieties as cabochons of large size, including green shades and also pink, translucent material. Massive white material from China has also been carved.

The Sri Lankan gem gravels have produced orange and brown grossulars (hessonite) up to several hundred carats. Although clean only in small sizes, the fine cinnamon colored hessonites from Quebec have yielded good cut gems up to about 25 carats.

While rare in clean gems over 1 carat, tsavorites in the size range of 10 to 20 carats do occur. A tsavorite crystal weighing 925 cts yielded a faceted 325-ct gem!

  • Smithsonian Institution (Washington, DC): 64.2 (orange-brown, Sri Lanka).
  • Private Collection: 13.89 (yellow, oval).
  • American Museum of Natural History (New York): 61.5 (cameo head of Christ, hessonite).
  • National Museums of Canada (Ottawa, Ontario): 23.94, 13.40, 8.50 (brownish-orange hessonite, Asbestos, Quebec); 4.68, 2.94 (colorless, Asbestos, Quebec).
grossular garnet colors
This display at the National Museum of Natural History, Washington DC demonstrates the multiple hues grossular garnets can show. “Grossular Shades” by Alkivar. Public domain.

Care

Although garnets can make beautiful jewelry stones, grossulars straddle the hardness range of 6.5 to 7.5. Thus, some specimens may resist scratching from household dust while others won’t. Before choosing a jewelry setting for your grossular, ask your vendor or a gemologist about its hardness.

Smithsonian bars and brilliant pears make good design choices for faceting light-tone grossulars. Tic tacs and checkerboards make good choices for dark-tone grossulars, like tsavorites. (Note: Read Jeff Graham’s comments on faceting grossulars and Donald Clark’s advice on cutting garnets for additional recommendations).

Grossulars have some heat sensitivity and may contain inclusions. Thus, avoid mechanical cleaning systems and exposing them to extreme heat. Instead, use warm water, detergent, and a soft brush for cleaning. Consult our jewelry cleaning guide for more recommendations.

Faceted Grossular - South Africa and Tanzania
Grossular Garnet: South Africa, cabochon, (4.1). All others, Tanzania (ca 1 to 6.5). Photo © Joel E. Arem, PhD, FGA. Used with permission.