Garnet Quality Factors

Garnet Quality Factors
Garnet comes in as wide a variety of sizes and shapes as well as colours.
Garnets are a group that includes a number of different minerals, so appearance can vary widely. The first thing a buyer of garnets needs to be aware of is the wide variety of garnet types.

At first, the sheer number of garnet varieties can seem bewildering. It helps to think of the different types of garnets in terms of colour.
Pyrope and almandine range in colour from purple to orangey red. Spessartine is found in a variety of orange colours, while andradite comes in yellow and yellowish green. Grossular has perhaps the widest colour range of any garnet species, from colourless to yellow to reddish orange and orangey red, to a strong, vibrant green.

Spessartine garnets from the US state of Virginia
These vibrant spessartine garnets are from the US state of Virginia, another important historical source for collectors. - Gift of John Bradshaw
68.82 Carat Tsavorite Garnet
This tsavorite garnet has an appealing green colour and is a 68.82-carat gem. - Courtesy New Era Gems
3.20 Carat Demantoid Garnet
This 3.20-carat demantoid garnet’s vivid green hue is exceptionally beautiful. In fact, it’s close to the top colour for this variety. The gem is mounted in a platinum ring with diamond accents. - Courtesy A Touch of Color
Gemmologists and coloured stone dealers further subdivide some garnet species into varieties depending on colour. For example, demantoid is a brilliant green variety of andradite that’s highly prized by collectors. Both tsavorite and hessonite are varieties of grossular. Tsavorites are green, while hessonite ranges from orange and orangey red to brownish red. Rhodolite is a purplish red variety.

8.72-carat pyrope-almandine garnet
Rhodolite is the purplish variety of pyrope-almandine garnet. It can be spectacular, like this 8.72-carat gem.
Typical garnet clarity depends on garnet type. For example, the red garnets almandine, pyrope and rhodolite typically do not have eye-visible inclusions. Some of the orange garnets, like spessartine and hessonite, often have eye-visible inclusions.

Hessonite garnet
Hessonite garnet often has a turbulent inner appearance called the roiled effect. - © GIA & Tino Hammid, courtesy Gordon Bleck
Demantoid garnet with horsetails
Demantoid might have eye-visible inclusions called horsetails that can raise its value.
Grossular is typically translucent, making it popular for cabochons, beads and carvings.

Many garnets are cut into standard shapes and standard sizes to allow easy setting into jewellery. This is especially true of many red garnets. Expensive garnets like fine-quality tsavorite are cut into shapes and cutting styles that allow more of the weight to be retained from the rough.

Garnets in a variety of shapes and cutting styles
Garnets come in a variety of shapes and cutting styles.
Demantoid is often cut to exact proportions that allow the best possible display of its fire. Garnets are also popular for designer cuts and carvings. Red garnets are classic materials for cutting into cabochons and beads. They are commonly found to have high clarity and to be very transparent.

Carat Weight
Garnets can be found in all sizes and weights. Some garnets, like demantoid and tsavorite, are more commonly found in small sizes, so their value goes up significantly with size. Other garnets, like almandine, are far more common in larger sizes so there’s no dramatic rise in value as size increases.