All Garnets essentially have the same crystal structure. However, they vary in their chemical compositions and respective colors.
Over twenty Garnet categories exist, but only five are considered commercially important gems. The five include Almandine or Almandite, Pyrope, Grossular or Grossularite, Spessartine, and Andradite.
Garnets have to be one of the more confusing stones to collect because there are so many different shades of red, purple, green, orange, and even pink. Then you have to take into consideration where they’re mined. This also plays a role in what type of Garnet you have.
I’ll do my best to outline the most popular varieties and give a little insight on how to quickly identify them.
Types of Garnet
Garnets are closely related minerals that form a group of gems with almost every color of the rainbow. While Red Garnets have a lengthy history, these days, we can find a rich array of hues, including greens, oranges, pinkish-orange, purplish reds, and a few shades of blue.
Pro tip: Blue Garnetes are pretty rare and hard to source. So, if you see someone selling large stones or large quantities then it is most likely fake or synthetic.
Almandine is one of the most common members of the Garnet group. If you’re a rockhound then you’ve screened for these in rivers and dug them out of matrix.
The commercial value for this type of Garnet is fairly low due to oversupply and the dark red color. With that said Almandine makes for great specimens and great material for cabbing and faceting if you’re on a budget.
The crystal structure on Almandine Garnet is well defined and this helps with identifying it quickly because other varieties will be lacking crystal structure but show more of an alluvial structure.
Pyrope is a dark, blood-red hue that’s distinct and incredibly attractive, which makes it a great gemstone for jewelry. Most of the faceted Garnet you see at the jewelry store is the Pryope variety.
In the gem trade, Pyrope (the term) is rarely used on its own. You will find it either generically referred to as Garnet or Pyrope Garnet. Regardless, they’re all the same stone.
Rhodolites describe the rose-red form of Garnet, which has a lighter tone and more of a purplish color. These gems are usually an intermediary variety somewhere between the Almandine and Pyrope varieties.
Rhodolite typically contains more magnesium than iron, which actually leans closer towards Pyrope and is often regarded as a variety of Pyrope.
Most of the rough material will be in shards or water-worn pebbles. Rarely do you see a strong crystal structure with Rhodolite Garnet.
Mahenge is a newer stone that was found in 2015. It is a combination of Almandine, Pyrope, and Spessartine. Most of these Garnets are available in a range of colors from pink to purple, with some that display a color shift from pinkish-red to purple, depending on the light source.
The unique thing about Mahenge Garnet is its refractive index. For some reason, these stones have more dispersion when compared to other Garnet varieties. This makes them highly sought-after and larger stones will demand a premium.
Spessartite Garnets display a better red hue and the saturation is higher than your typical Pyrope or Almandine Garnet. For this reason, this material is popular among lapidary artists and jewelry designers.
Some of the material will have a secondary orange flash. You’ll notice this when viewing faceted stones. This is the more valuable color among the Spessartite material.
Hessonites are a variety of Grossular Garnets with colors ranging from golden yellow to brownish orange or brownish-red. Perfectly colored Hessonite displays a bright golden orange that resembles a combination of orange and honey with a beautiful internal fire.
Now you’re probably wondering how to tell the difference between Hessonite and Spessartite. You’re going to need time and a 10x loop. The more time you spend with gemstones and crystals the better you’ll be at quickly identifying them correctly.
The answer is simple. Hessonite has sugar-like inclusions and Spessartite doesn’t.
Merelani Mint Garnets are found in Tanzania and are named after the region in which they’re sourced. The light minty green color is a favorite among collectors and relatively unique, to say the least. Don’t confuse these with the deeper-colored Tsavorite Garnet.
High-quality material is available but it is becoming harder to source. The rough crystals are quite amazing to look at on their own but faceted material holds its own against precious gemstones.
Tsavorite Garnets bring extremely high values on a per-carat basis. Top color with a high clarity grate are difficult to obtain and stones over 5 carats are rare.
When it comes to color the light-colored grades are relatively easy to come by and the deeply saturated stones that are pure green in color command the highest prices.
This is the rarest variety of Garnets but high-quality material is almost non-existent because most crystals have flaws and horse-tail-like inclusions.
Demantoid was initially mined in Russia but now we know of several localities where this beautiful stone can be found.
Mali Garnets are semi-precious gemstones and they sometimes go by a different name, Grandite. These stones display yellow, green, and brown hues. While many are familiar with Red Garnets, here we have a beautiful green shade that is rare and among the most valuable of the variety.
Color Change Garnet
Most Garnets, but not all, that display color change are a mix of Pyrope and Spessartite.
If you’re a rockhound in the Pacific Northwest then you’re in luck because Garnets sourced from Idaho have the unique mix of Pyrope and Spessartite which means you have a chance to dig for your own color-change Garnets.
If you’re more into gemstones then you’ll want to focus on Mali Garnets because they have a strong tendency to display color change from grayish greens in fluorescent lights to brown in incandescent lighting.
Pro tip: Don’t confuse “color shift” with “color change”. There is a big difference and you don’t want to overpay for material that is not a true color change Garnet.
Star Garnets are a unique variety of Garnet that displays a multi-rayed light reflection on their surface that resembles a star. The optical phenomenon is called Asterism. This stunning effect is incredible and can also be found in the Star Ruby. For anyone wondering, yes, these stones are natural, which is why they’re so highly prized.
Uvarovite Garnets were first discovered by Gremain Henry Hess in 1832, and it was named after the Russian statesman Count Sergery S. Uvarov. This stone is often mistaken as an Emerald because of the similar display of deep green color.
Most of the crystals will be attached to matrix and often in Druzy groupings. These beautiful specimens can be found in England, Poland, Russia, Australia, India, South Africa, and the USA (in New Mexico and Arizona).
Top 3 Garnet Varieties For Collecting
Now that you’ve educated yourself on the most popular varieties of Garnet we need to narrow the list down to the top three for your personal collection. Without a doubt I would start with Tsavorite because of the intense green color and the material is becoming harder to source. Then I would add a Mahenge Garnet to the collection because of its unique refractive index and limited supply. Last but not least I would add a Mali Garnet because you don’t see a lot of high-end material in the open market.