Garnets are a varied group of gemstones that share similar properties. The traditional variety is dark red however a large amount of other colors have recently become available. The typical deep red garnets are a very common and inexpensive gem, however the rarer varieties like green garnet (Tsavorite) can be as valuable as precious stones like emerald. The groups are separated by their different chemical compositions:
Almandine – Dark Purplish Red
Pyrope – Dark Red
Spessartite – Orange
Grossular – Green or Yellow
Andradite – Green or Brown
Curiously, the above groups of garnets often intergrade and form new varieties. These “hybrid” garnets often come in unusual colors which makes them great for someone looking for something unique.
Garnet is a hard-wearing gem with a hardness of 7-7.5 and good toughness. Due to their high refractive index, garnets are a fiery and sparkling gemstone, particularly in light to medium tones. It is the traditional birthstone for January. Some of the types of garnets available are as follows:
This is a blanket term to describe garnets of deep red to brownish red color which belong to the pyrope and almandite groups. These are the most common and inexpensive garnets. Lighter toned stones are more valuable than very dark stones.
Rhodolite and Umbalite Garnet
Rhodolite garnet is a mix of almandite and pyrope garnet which has a pink or pinkish-red color. It is more valuable than plain red garnets but still quite inexpensive in the smaller sizes. Large good color stones are rare and command higher prices. Umbalite is a rare form of rhodolite from East Africa with a light to medium toned pink-purple color.
Malaia (sometimes spelled Malaya) garnet is a hybrid garnet that occurs in a wide variety of colors. It is most often reddish-orange or pinkish orange. It can also rarely be found in light brown, peach, light pink and champagne. It is sometimes known as imperial garnet, though this typically only refers to the lighter toned stones. A light orange-pink variety called Mahenge garnet has recently become available from Tanzania and is becoming very popular.
Purple Garnet (Roshoite)
A new variety of fancy garnet recently discovered in Mozambique is purple garnet. This is a type of rhodolite that has a strong purple color. These stones often have a color change from reddish cranberry to grape purple in different light sources. Due to its popularity, prices for this gem have risen sharply and continue to rise due to very limited production. Sizes are generally small and quality gems over two carats are rare.
Another rare garnet recently to emerge from East Africa is yellow grossular garnet. This is from the same group of garnets as tsavorite. These stones have fantastic luster and brilliance. They vary from pastel yellow to rich golden yellow. All garnets have a hardness of 6.5-7.5 which makes them suitable for all types of jewelry. They also have a high refractive index, which gives them a lot of sparkle. This is particularly noticeable in light to medium-toned stones, which are usually more valuable than dark stones.
Please refer to Tsavorite.
Mineral Group: Garnet
Crystal Structure: Cubic or rhombic dodecahedron
Luster: Vitreous to sub-adamantine
Specific Gravity: 3.1–4.3
Refractive Index: 1.72 – 1.94
Double Refraction: None
Treatments: No treatments
Color: Nearly all colors