Garnets – Not Only Red – What a Variety!

Garnet are durable, beautiful and come in a variety of colours.  Garnets are well suited to both traditional settings and more modern settings.  Due to the varieties of garnets available, there are garnets at all price levels.   Meet a gemstone variety where visible inclusions add value to the stone.

Variety of Colour of Grossular Sarnet

Grossular Garnet Colours - Photo by J McKercher

There is a  common perception that garnets are a low-priced red gemstone, this comes from the predominant use of the red varieties of garnet called Almandine and Pyrope.  Garnets come in all colours.

Blue Garnets and Horse Tails

In 1998 there was a discovery of a colour-change blue to red/pink material in Bekily, Madagascar. These stones are very rare. Colour-change garnets are by far the rarest garnets except Uvarovite, which does not come in cuttable sizes.
In daylight, their colour can be shades of green, beige, brown, grey and rarely blue, to a reddish or purplish/pink colour in incandescent light. It is expected that blue colour-change garnets will match Alexandrite prices or even exceed them as the colour change is often better and these garnets are much rarer.
Pronounced chrysolite asbestos fibers are typically seen in green Demantoid garnet as an inclusion, often they form in a curved radiating bundle of fibres that look like a horse-tail. If these inclusions are placed in the centre of a faceted Demantoid garnet they actually make the gemstone more valuable!

Variety of Colours

Tsavorite Grossular Garnet

Tsavorite Grossular Garnet Photo by J McKercher

The varieties of garnet are coloured by the elements that are present as an essential element in the chemical composition of the gemstone, or the element is found in the gemstone as an impurity. The replacement of one element in the chemical composition of a mineral (either partly or completely) be another element having the same valency is called isomorphous replacement.  The structure or form of the crystal is not radically altered, but wide variations in the physical properties (such as the colour) of the mineral may result.

Grossular Garnet from Mexico

Grossular Garnet Photo by J McKercher

Rhombic Dodecahedron

When garnets are found they usually form in a habit called a rhombic dodecahedron, and are often found in clusters.  This means that each crystal has 12 faces and each face is rhombus shaped (a squashed diamond shape).  Most science museums have a variety of beautiful faceted and rough garnets.

Andradite Garnet from Mexico

Andradite Garnet Photo by J McKercher

Some garnets will be attracted to a magnet

Once I purchased a very inexpensive ruby ring online. When it arrived it was very obvious by the inclusions that it was an Almandine garnet, but before I used a microscope I did a very simple test with a magnet. Almandine and Rhodolite garnet and Spessartine, yellow Andradite (with iron) will be slightly attracted to a magnet. Ruby will never be attracted to a magnet!

Your Input (Join our poll or Scroll Down To The Bottom and leave a comment) – Emerald is winning the poll!

Spessartite Garnet

Spessartine Garnet Photo by J McKercher

I plan to introduce different gemstones alphabetically.  I will start with “A” (Ammolite) and see where it leads me.  Leave a comment and let me know if you have a favourite gemstone that starts with the letter “H”.  Take the poll!  Can you name a reference to a gemstone in a song, movie or book?


About Jen McKercher

Jennifer McKercher teaches gemmology at the Canadian Gemmological Association. A passion for gemstones drives Jen to learn as much as she can about the wonders of gemstones and how they enhance our lives.

Posted on August 11, 2011, in Individual Gemstones and tagged , , , , , , , . Bookmark the permalink. Leave a comment.

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