Garnet Value, Price, and Jewelry Information

In this comprehensive guide to garnet gemstones, you'll discover:

• How the complex garnet family consists of multiple species and varieties with unique characteristics and values.
• The distinctive properties of each garnet type including almandine, andradite, grossular, and the prized green garnet varieties.
• What factors determine garnet value and which varieties command the highest prices in the jewelry market.
• How to identify different garnet varieties through their physical and optical properties.
• Essential care guidelines to maintain the beauty of your garnet jewelry for generations.

Understanding Garnet Nature and Diversity

Unlike minerals such as corundum or beryl that are a single species with colored varieties created by trace elements, garnets come in different species and are never found in their pure state. They always exist as a mixture with other garnet species. Gemologists classify garnets as a solid-state series or a blend. Some of these blends have distinctive features and are recognized as varieties of garnets in themselves. What unifies all garnets is their identical crystal structure and similar properties.

Major Garnet Species: Colors, Properties, and Values

For more information on these species and their own varieties, click on the links to the individual listings.

Almandine: The Classic Red Garnet

Almandines represent the most common gemstone in the garnet family. These garnet stones come in a wide range of colors. The blend of almandine-pyrope creates the dark red variety popularly associated with traditional garnet jewelry and rings.

Andradite: The Most Brilliant Garnet Variety

Andradites rank among the rarest garnets, featuring the highest dispersion of all garnet varieties—even exceeding that of diamond. Demantoids, a green garnet variety of andradite, are especially prized by collectors and command premium prices.

Grossular: The Most Colorful Garnet Species

Unlike other garnets, grossulars rarely appear red or dark in tone. However, they occur in virtually every color except blue, including colorless specimens. Their light to medium tones and vibrant colors make grossulars excellent jewelry stones. Tsavorites, with their emerald-like green color, can command high prices, while hessonite "cinnamon stones" remain popular and affordable garnet options.

Hydrogrossular: The Opaque Garnet Variety

Hydrogrossulars never achieve transparency and typically appear blueish green, though they occasionally occur in pink, white, and gray.

(Editor's note: the classification of hydrogrossular as a garnet species is debatable).

Pyrope: The Ruby-Like Garnet

Chrome pyropes display a red color that can rival fine rubies. However, these garnet stones typically feature a very dark tone that distinguishes them from rubies.

Spessartite: The Orange Garnet Gem

Also known as spessartines, spessartites represent somewhat rare garnets that display a variety of orange hues. Mandarin garnets, a variety of spessartite with a striking orange color, are highly sought after by collectors and jewelry enthusiasts.

Uvarovite: The Emerald-Green Garnet

Uvarovites represent the rarest member of the garnet family. These green garnet stones display a dark, rich green color that rivals emerald. Facetable uvarovite material remains even rarer and always small in size.

Non-Gem Garnet Species: Collector Specimens

Non-gem garnet species include goldmanite, henritermierite, kimzeyite, majorite, schorlomite, and yamatoite. While not used in jewelry, these garnet varieties may interest collectors of rare mineral specimens.

How Do Garnet Blends Create Unique Jewelry Stones?

The following blends are considered varieties of garnet rather than sub-varieties of the above species.

Rhodolite: The Purple-Pink Garnet

Rhodolites blend pyrope and almandine to create a distinctive purplish color that sets them apart from other garnet gemstones.

Malaya or Malaia Garnet: The "Out of Category" Gem

This term originally described malaya or malaia garnets that didn't fit into standard categories. Now, gemologists recognize them as a blend of pyrope and spessartite, displaying various shades of orange, red-orange, peach, and pink.

Color Change Garnet: The Chameleon Stone

In recent decades, gemologists have discovered color change garnets that transform to blue under artificial light. In the late 1990s, blue garnets that appear red with purple flashes under incandescent light emerged from Madagascar. These color-changing stones represent a pyrope-spessartite blend. Some Idaho garnets demonstrate a strong color shift from red to purplish red. These garnet stones form an almandine-pyrope mix.

The following species commonly blend together:

• Almandine-pyrope
• Almandine-spessartite
• Andradite-grossular (also known as grandites on Mali garnets)
• Pyrope-spessartite

How to Identify Different Garnet Varieties

Identifying garnets presents numerous challenges. In the last fifty years, gemologists have discovered several new blends in East Africa. There's no reason to assume we've found all possible garnet blends. The future likely holds more discoveries for gemologists.

Despite considerable variations, garnets share common properties at the molecular level. For those without scientific backgrounds, here's a helpful visualization: If your hand represented a garnet molecule, all garnets would share the atomic arrangement represented by the palm. However, the atoms represented by your fingers could interchange. Different atoms can occupy these positions while the palm remains constant. Changing the chemistry creates a different species. Substitute the atoms of a finger and you have a different species, even though the structure and related properties remain essentially the same.

Garnet Chemistry: The Foundation of Diversity

The chemistry of garnets varies far more than the hand model can accurately demonstrate. Below is the chemical composition of the main gem garnet species:

• Almandine: Fe₃Al₂Si₃O₁₂
• Andradite: Ca₃Fe₂Si₃O₁₂
• Grossular: Ca₃Al₂Si₃O₁₂
• Hydrogrossular: Ca₃Al₂(SiO₄)_3-x(OH)_4x
• Pyrope: Mg₃Al₂Si₃O₁₂
• Spessartite: Mn₃Al₂Si₃O₁₂
• Uvarovite: Ca₃Cr₂Si₃O₁₂

As evident, garnet chemistry shows several variations. Nevertheless, all maintain the same basic structure. Garnets crystallize in the isometric system. Their most common forms include the trapezohedron and dodecahedron. Interestingly, garnets rarely form as cubes or octahedrons, which represent the most common shapes of other isometric minerals. Garnets may also appear massive, granular, or as tumbled pebbles.

For decades, gemologists described rhodolite as one part almandine and two parts pyrope. However, garnet composition proves more complex. Rhodolite gems, like all garnets, contain traces of other species in the mix. These may appear in minute amounts, but garnets never consist of just two components. Furthermore, a solid-state series like an almandine-pyrope blend doesn't indicate a mixture of two molecule types (Fe₃Al₂Si₃O₁₂ and Mg₃Al₂Si₃O₁₂). Instead, it means the structure contains both Fe and Mg elements.

Are Pure Garnets Found in Nature?

In nature, garnets don't form as a single pure species. The purest gem-quality pyrope ever discovered contained approximately 83% pyrope, 15% almandine, and about 2% other garnets. Similar patterns occur with almandine and grossular, where 80% represents the highest purity typically encountered. However, andradite and spessartite garnets have been found with up to 95% purity. Non-gem sized, colorless garnets of 97% pure pyrope provide hope for those seeking purity in the garnet world.

How Gemologists Describe Garnet Compositions

Traditionally, gemologists described garnets as a straight-line series, such as almandine-pyrope or pyrope-spessartite. However, this approach fails to adequately explain the complex blends we now recognize.

A more effective description employs a two-dimensional graph, with almandine, pyrope, and spessartite marking the three corners. A gem's chemistry would rarely fall on one of the flat sides. In reality, it would appear as a point inside the triangle, indicating the proportion of each element present.

For complete accuracy, a three-dimensional model works best, adding andradite, grossular, and uvarovite to the formula. While less common, grossular and andradite occur in almost all garnet blends. With this graph, one can indicate how much of each species exists in an individual specimen.

Understanding garnet blends holds importance for gemologists. Today's known garnets display considerable variations in their mixtures. Standard practice identifies garnets by their two primary species unless it's a common variety. Just remember that garnets aren't simple, two-species minerals.

Historically, gemologists grouped garnets according to chemical composition, a nomenclature that persists today. Garnets containing Al (aluminum) in the B position of their chemical formula are known as pyralspites (for pyrope, almandine, and spessartite). Garnets with Ca (calcium) in the A position are called ugrandites (uvarovite, grossular, and andradite).

Optical Properties of Garnet Stones

These properties depend heavily on chemistry. Pyrope, almandine, and spessartite are generally isotropic. However, the presence of the large Ca (calcium) atom in uvarovite, grossular, and andradite makes them birefringent. This may result from strain but more likely has a structural explanation. Grossular and andradite almost always appear zoned, often twinned, and distinctly not isotropic under the microscope.

Garnet Colors: A Rainbow of Possibilities

Due to garnet's tremendous range of overlapping colors, gemologists cannot identify this gem based solely on color. The following information serves as reference only:

• Uvarovite: dark green.
• Grossular: colorless, white, gray, yellow, yellowish green, green (various shades: pale apple green, medium apple green, emerald green, dark green), brown, pink, reddish, black

• Andradite: yellow-green, green, greenish brown, orangey yellow, brown, grayish black, black. The color is related to the content of Ti and Mn. If there's little of either element, the color is light and may resemble grossular.
• Pyrope: purplish red, pinkish red, orangey red, crimson, dark red. Note: Pure pyrope would be colorless; the red colors come from Fe + Cr.
• Almandine: deep red, brownish red, brownish black, violet red.
• Spessartine: red, reddish orange, orange, yellow-brown, reddish brown, blackish brown.
• Malaia: various shades of orange, red-orange, peach, and pink.
• Rhodolite: usually has a distinctive purplish color.

Synthetic Garnet Varieties

Synthetic garnets have significantly impacted the gem world. Before the introduction of cubic zirconia in the late 1970s, synthetic garnet served as the primary diamond simulant. While they maintain a smaller presence in today's market, these synthetic gems remain available.

YAG: The First Synthetic Garnet

YAG, or yttrium aluminium garnet, pioneered the synthetic garnet jewelry market. In its pure state, YAG appears colorless. However, manufacturers can create it in nearly every color. The dopants used for coloring also affect the wide range of refractive index and specific gravity. Colorless YAG registers at the lower end of these properties. YAG demonstrates good durability and wears well. However, its dispersion falls somewhat low for an effective diamond substitute.

GGG: The High-Dispersion Synthetic

GGG, or gadolinium gallium garnet, features high dispersion (.038). Gadolinium and gallium cost significantly more than yttrium. However, with dispersion approaching diamond (.044), GGG makes an excellent substitute. As with YAG, coloring dopants affect the refractive index and specific gravity ranges. Colorless GGG registers at the lower end of these properties. Less expensive cubic zirconia has largely replaced GGG in modern jewelry. Nevertheless, these synthetics remain available in numerous colors. They produce beautiful cut gems and remain popular among many lapidaries.

Garnet Enhancements: The Proteus Treatment

In Greek mythology, Proteus was a shape-shifting sea god whose name now describes someone who easily changes appearance or principles. "Proteus garnets" represent the only regularly treated garnets. A few almandine-pyrope gems from the US transform into Proteus garnets through treatment. All other types resist change. This treatment creates a thin layer of metals on the stone's surface, giving it a dual appearance. In reflected light, Proteus garnets display a dark gray, metallic luster similar to hematite. In transmitted light, the dark red color shows through.

What Size Garnet Gemstones Are Available?

Garnet crystals typically range from microscopic up to about 6 inches for grossular specimens. Many deposits consist of small crystal grains in or on their host rock. Garnets embedded in rock with poor external forms may grow much larger, like the almandine from Gore Mountain, New York, which reaches 60 cm in diameter. A few spessartites from Brazil have weighed several pounds while maintaining excellent transparency and color. However, these remain exceptionally rare. A typical garnet crystal measures about half an inch to an inch in diameter.

How to Care for Your Garnet Birthstone Jewelry

Clean garnet gemstones with warm water, mild detergent, and a soft brush. Although relatively hard and durable, garnets can be heat sensitive. Avoid using extreme heat for cleaning or repairs. See the individual entries for specific species and varieties for additional recommendations. Consult our Gemstone Care Guide and Gemstone Jewelry Cleaning Guide for more comprehensive information.