Garnet

On the nature of garnet

The earth produces garnets in an astounding array of colors.  These gemstones, while they vary widely in hue, are a set of closely related silicate minerals that are similar in their physical properties and crystal structures but find their uniqueness in their chemical composition. 

Garnets can be found in almost every color of the rainbow.  From the Gemological Institute of America.

Garnets can be found in almost every color of the rainbow.  From the Gemological Institute of America.

Red garnets have a long history, an ancient history: they have been used by mankind since the Bronze Age. Of all gemstones found in metamorphic rocks, red garnet is one of the most common: it can be found on every continent. That said, not all garnets are so easily located. While tsavorite is also found in metamorphic rocks, it is actually quite rare because of the special conditions and chemistries required for its creation.

68.82ct tsavorite garnet. From the Gemological Institute of America.

68.82ct tsavorite garnet. From the Gemological Institute of America.

Like tsavorite, several other colored garnets have their own special names. Demantoid is another rare green garnet, spessartine (also known as spessarite) is a much-coveted orange garnet, and rhodolite is a mystical purpley-red garnet. Garnets are also capable of exhibiting the miraculous color-change phenomenon, like the gemstone alexandrite.

But that's not all! There are more than twenty garnet categories, which are called species. But as far as gems are concerned, only five are important:

  • pyrope
  • almandine (almandite)
  • spessartine
  • grossular (grossularite)
  • andradite

There is also uvarovite. This is a green garnet with crystals that are usually too little to cut. It’s sometimes set as clusters in jewelry. Many garnets are chemical mixtures of two or more garnet species.

On finding garnet and what to look for

Garnet is common: it is found on every continent on our earth, although not every continent produces deposits that are of gem quality and worth mining. But when most people think of garnet they think of the red specimen of this fascinating gemstone family, the pyrope garnet. Throughout the ages and until the late 19th century, Bohemia was the main source of pyrope garnets.

A Victorian-era hair comb studded with pyrope garnets from Bohemia.  Smithsonian Institution.

A Victorian-era hair comb studded with pyrope garnets from Bohemia.  Smithsonian Institution.

Demantoid garnet was discovered in Russia’s Ural Mountains in 1851. From the time of their discovery and through the early 1900s they were quite fashionable in Russia. Carl Faberge's pieces from this period often featured specimens of demantioid. Beyond Russia's borders, Tiffany & Co. was also able to acquire this gemstone and used extensively at this time.

Later on in the mid 1900s, tsavorite was unearthed in northern Tanzania and in Kenya.  It remains popular and rather prestigious today.

Other significant deposits are located in Sri Lanka, Thailand, India, and the Middle East.

Garnets, like other precious gemstones, are evaluated by their color, clarity, cut, and carat weight.

Vivid orange spessartines, colorless diamonds, and green tsavorite garnets from Kenya are the gemstones in this piece by Buzz Gray and Bernardine Johnston. From the Gemological Institute of American.

Vivid orange spessartines, colorless diamonds, and green tsavorite garnets from Kenya are the gemstones in this piece by Buzz Gray and Bernardine Johnston. From the Gemological Institute of American.

Color. As you might suspect, one begins with color when considering the quality of a garnet.  Some colors are more prized than others depending on their rarity and fashion trends.  Pyrope and almandine garnet span the color wheel from purple to orange-red. Spessartine garnet is also found in a variety of orange colors. Andradite garnet can vary from yellow to yellowish green. Demantoid is a variety of andradite garnet that is a gorgeous hue of vivid green and quite coveted by collectors. The grossular garnets are probably the most variable of all garnets since their range begins with colorless and travels to yellow to orange to green and even a little bit beyond.   Green tsavorite, orange hessonite, and violet-red rhodolite are all part of the grossular garnet family.

Clarity. Clarity will depend on the type of garnet one is considering. Red garnets such as almandine, pyrope, and rhodolite do not usually have inclusions that are visible to the eye while many of the orange garnets do. That's not always a bad thing. For example, hessonite is capable of producing a stormy appearance that gemologists called the roiled affect. Another example is demantoid which can have inclusions called horsetails that often raise the stone's value.

Demantoid might have eye-visible inclusions called horsetails that can raise its value.  From the GIA.

Demantoid might have eye-visible inclusions called horsetails that can raise its value.  From the GIA.

Cut. First of all, many garnets, especially red garnets, are cut into standard shapes and sizes to allow for easy and economical setting into jewelry. However, valuable garnets like fine-quality tsavorite are cut to allow as much of the weight as possible to be retained from the rough. Demantoid will usually be cut in a way to show off its fire to the best advantage. Because they are so flawless and transparent, red garnets are commonly cut into cabochons and beads.

Carat. Garnets are be found in all sizes and weights but there is some difference depending on the species. Demantoid and tsavorite are usually found in rather small sizes, so their value increases significantly with size. On the other hand, some garnets such as almandine are actually common in larger sizes so the value doesn't rise significantly for high carat stones.

Historical notes and other interesting facts about garnet

Derived from a pomegranate. The name garnet might come from the Latin word 'granatum', meaning pomegranate. The red flesh of the pomegranate is similar to the color of many garnets.

Made in 200-100 BC, this ancient Roman necklace consists of a gold chain strung with garnet beads. From the Victoria and Albert M

Made in 200-100 BC, this ancient Roman necklace consists of a gold chain strung with garnet beads. From the Victoria and Albert M

Worn by mummies. Many thousands of years ago, necklaces of red garnet beads were worn by Egypt’s pharaohs and accompanied them to the afterlife in their opulent tombs.

Sealed with a garnet. Signet rings in ancient Rome held carved garnets to stamp the wax that secured important documents and letters.

Carbuncle. In ancient time, the term carbuncle referred to red garnets, although it was also used for almost any red stone -- including rubies!

Garnet cicadas. Garnets were the most popular stone used in Frankish and Merovingian jewelry. The tomb of the first Frankish king, Childeric (about 440-481), contained sword fittings set with garnets and 300 gold and garnet cicada ornaments.

The red almandine garnet surrounded by pearls suggests a flower, symbol of love. The red of the garnet was often used to symbolise passion whilst the pearls signified purity. The central garnet is engraved with two clasped hands, a motif known as a 'fede', from the Italian 'mani in fede' or hands clasped in trust. From the Victoria and Albert Museum in London.

The red almandine garnet surrounded by pearls suggests a flower, symbol of love. The red of the garnet was often used to symbolise passion whilst the pearls signified purity. The central garnet is engraved with two clasped hands, a motif known as a 'fede', from the Italian 'mani in fede' or hands clasped in trust. From the Victoria and Albert Museum in London.

Cabochons from Bohemia. Around 1500, red garnet’s availability increased with the discovery of the famous Bohemian deposits in central Europe. Most of the precious stones used in medieval jewelry came from such countries as Afghanistan, Burma, Sri Lanka, and India. Garnets, however, coming from Eastern Europe, were more readily available and affordable.

The color of passion. The red of the garnet was often used to symbolize passion.

In the house of Faberge. With the discovery of demantoid garnet in Russia's Ural Mountains, came in influx of special pieces, jewelry as well as object d'art, made with this green gem by fashionable and elite jewelers such as Carl Faberge.

Resources and further reading

The Gemological Institute of America's Gem Encyclopedia.

Gemstones of the World. By Walter Schuman.  Our go to book at Grimballs.

Jewels: A Secret History. By Victoria Finlay.  An non-fiction adventure through time and place exploring the history of gems.

Smithsonian Institution National Museum of Natural History's Gem Gallery.