Thursday, December 29, 2016

Almost everything you ever wanted to know about Garnet.

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.

Garnet Varieties 

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. )   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 Uses

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:
  • Almandine
  • Pyrope
  • Spessartite
  • Grossular
  • Andradite
  • Uvarovite

Here is a list of the general Garnet variety names that are commonly used along with a general description:
This list and the pictures below were borrowed from

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
Almandine Garnet Rough
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

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