Garnets are a set of closely related minerals that form a group, resulting in gemstones in almost every colour.  Red garnets have a long history, but modern gem buyers can pick from a rich palette of garnet colours: greens, oranges, pinkish oranges, deeply saturated purplish reds, and even some blues.
 
Red garnet is one of the most common and widespread of gems, found in metamorphic rocks (which are rocks altered by heat and pressure) on every continent.  But not all garnets are as abundant as the red ones.  A green garnet, tsavorite, also occurs in metamorphic rocks, but it’s rarer because it needs unusual rock chemistries and special conditions to form.


 
Demantoid is a rare and famous green garnet, spessartine (also called spessarite) is an orange garnet, and rhodolite is a beautiful purple-red garnet.  Garnets can even exhibit the colour-change phenomenon similar to the rare gemstone alexandrite.

Thousands of years ago, red garnet necklaces adorned the necks of Egypt’s pharaohs, and were entombed with their mummified corpses as prized possessions for the afterlife.  In ancient Rome, signet rings with carved garnets were used to stamp the wax that secured important documents.

Quality Factors

Colour

Garnet includes affordable dark red varieties, rare and valuable greens, and many colours in between.

Clarity

Garnet clarity often depends on garnet type.  Red garnets often don’t have eye-visible inclusions.

Cut

Many garnets are cut into standard shapes and calibrated sizes to allow setting into manufactured jewellery.

Carat Weight

Garnets can be found in all sizes and weights, although some varieties are rare in large sizes.