It's All About Garnets!
It is also the January birthstone. When you think of garnet, you think of a red or dark burgundy red Pyrope Garnet. Well, those colors are the most well recognized, however, garnet is mined in a myriad of colors from the rich green tones of Tsavorite Garnet to the flaming orange of Mandarin Garnet. Garnets are considered to be a great gift and is a symbol of friendship and trust.
Garnets are classified as silicate minerals and have been used as abrasives and gemstones since the Bronze Age. Every species of garnet possesses similar crystal forms and physical properties, but have different chemical compositions.
Pyrope and Almandine Garnets are the most well known and widely used gemstones. Almandine is usually opaque and not used in as a gemstone. Only the less common dark red forms that are transparent are used as gemstones. Because Pyrope is known for its transparency and lack of inclusions and flaws, it is widely used in the gem trade. An intermediary between Pyrope and Almandine is known as Rhodolite Garnet is also very well represented in the trade.
Spessartite Garnet is a flaming orange to fiery orange-red gemstone that has just recently become popular. New deposits of this type in gem grade quality stones have been recently discovered and exploited.
Grossular Garnet has the most color variations. The most important being a variety of green Tsavorite and the orange-brown Hessonite. It is also found in a yellow to yellow-green form.
Andradite is the most lustrous of all the Garnets. It includes the rare yellow Topazolite variety, the black Melanite variety and the green Demantoid variety. The rarest variety of familiar garnet is
Uvarovite. It is rarely found in crystals large enough to be cut or faceted and is the least represented in the gem trade.
The color-changing garnet is a most interesting form of the family of garnet gemstones. It has a different color when viewed in incandescent lighting and natural lighting. It can also have many different color combinations. Color-changing garnets may be brown or orange in daylight and pink or light red under incandescent lighting.
The Star Garnet is a very rare variety that displays asterism (Def. - Mineralogy. A property of some crystallized minerals of showing a star-like luminous figure in transmitted light or, in a cabochon-cut stone, by reflected light. http://www.dictionary.com/browse/asterism?s=t ) in the form of a four-rayed star. Star Garnets are extremely rare and are usually opaque with a weak asterism making gem trade interest in this variety very limited. Star Garnet is found in Idaho.
Garnet is a popular gemstone. Almandine and Pyrope Garnets are used to make all kinds of jewelry (e.g.: Rings, necklaces, bracelets and earrings) because they are the most affordable. The rare green Demantoid and Tsavorite Garnets are the most costly and make exquisite faceted gemstones.
Forms and Varieties of Garnet
The six most popular and well known Garnet minerals are:
Here is a list of the general Garnet variety names that are commonly used along with a general description:
- Color-Change Garnet - Garnet that exhibits a different color in natural and artificial light. Color-Change Garnet is a intermediary mix between the Pyrope and Spessartite (though closer in composition to Pyrope), and presents a color change from a light brownish, yellowish, or greenish in daylight to a pink or purplish color in incandescent light. A few rare specimens may even have a bluish color, which is extremely rare for Garnet.
- Demantoid - Olive-green to emerald-green gem variety of Andradite Garnet.
- Gooseberry Garnet - Light green to light greenish-brown variety of Grossular Garnet.
- Hessonite - Orange to orange-brown, transparent variety of Grossular Garnet.
- Imperial Garnet - Light pink, transparent gem variety of Grossular Garnet.
- Leuco-garnet - Colorless, transparent variety of Grossular Garnet.
- Malaya Garnet - Reddish-orange form of Spessartite Garnet (or more accurately a mixture intermediary between Spessartite and Pyrope) that originates in the Umba River Valley in Tanzania and Kenya. This term is sometimes also used as a synonym for Spessartite.
- Mali Garnet - Garnet gemstone from the African country of Mali that ranges in color from green to yellow to brown (though most often a greenish-yellow). The deposit of these Garnets was discovered in Mali in 1994, and this form of Garnet is a relatively new gemstone. The scientific classification of the Mali Garnets are not clearly identified; they can be either Grossular or Andradite, though are usually an intermediary form closer in chemical structure to Grossular.
- Mandarin Garnet - Bright orange to orange-red Spessartite Garnet, usually originating from the African countries of Namibia and Mozambique.
- Melanite - Lustrous, opaque black or very dark red variety of Andradite Garnet.
- Mint Garnet - Grossular Garnet with a light-mint-green color.
- Mozambique Garnet - Red Garnet from the African country of Mozambique, which produces fine quality Garnet gemstones. Mozambique Garnet is usually Almandine, but may also be Pyrope.
- Raspberry Garnet - Raspberry-red variety of Grossular Garnet.
- Rhodolite - Rose-red form of Garnet with a light color or more purplish color than typical Garnet gemstones. It is usually an intermediary variety between Pyrope and Almandine, though more closely towards Pyrope in composition.
- Star Garnet - Form of Almandine Garnet that exhibits asterism in the form of a four-rayed star.
- Tangerine Garnet - Light orange to orange-yellow Spessartite Garnet, usually originating from the African countries of Namibia and Mozambique.
- Topazolite - Yellow to brownish-yellow variety of Andradite Garnet.
- Tsavorite - Green to emerald-green transparent variety of Grossular Garnet from Africa.
Garnet Enhancements & Treatments
Garnet gemstone colors are always natural and are not enhances. Treatments such as irradiation and heat treatment have been ineffective on Garnet gemstones. Many synthetic Garnets are imitations of other gemstones. The most well known synthetic Garnet is Yttrium Aluminium Garnet which is a colorless simulant of Diamond. It was frequently used until the 1970's, but was replaced by Cubic Zirconia as an imitation Diamond. Gadolinium Gallium Garnet is yet another form of Garnet. It is rarely ever used as a gemstone and is typically produced for optical and industrial uses.
Here are a few examples of the different forms and varieties of Garnet:
|Almandine Garnet Faceted|
|Pyrope Garnet Raw|
|Tsavorite Garnet Rough|
|Pyrope Garnet Faceted|
|Demantoid Garnet Faceted|
|Tsavorite Garnet Faceted|
|Color Changing Garnet Faceted|
|Demantoid Garnet Rough|
|Spessartite Garnet Faceted|
|Rhodolite Garnet Rough|
|Rhodolite Garnet Faceted|
|Spessartite Garnet Rough|
|Melanite Garnet Rough|
|Hessonite Garnet Rough|
|Uvarovite Garnet Rough|
|Topazolite Garnet Rough|
|Grossular Garnet Rough|
|Grossular Garnet Faceted|