Garnet
Garnets are a set of closely related minerals forming a group, with gemstones in almost every color.
OVERVIEW
ABOUT GARNET
Red garnets have a long history, but modern gem buyers can pick from a rich palette of garnet colors: greens, oranges, pinkish oranges, deeply saturated purplish reds, and even some blues. Red garnet is one of the most common and widespread of gems. But not all garnets are as abundant as the red ones. A green garnet, tsavorite, is rarer and needs rarer rock chemistries and conditions to form.
Birthstones & Anniversaries
Garnet is the birthstone for January and the gem for the second anniversary.
Tsavo Park
Campbell Bridges mined tsavorite garnet in Kenya near Tsavo National Park.
Faberge
The imperial Russian jeweler created intricate jewelry designs for demantoid garnet.
3800 BC
A stylish red garnet bead necklace found in a grave in Egypt is more than 5,000 years old.
FACTS
Mineral: Garnet group
Chemistry:
Almandine- Fe₃Al₂(SiO₄)₃
Andradite- Ca₃Fe₂(SiO₄)₃
Grossular- Ca₃Al₂(SiO₄)₃
Pyrope- Mg₃Al₂(SiO₄)₃
Rhodolite- (Mg, Fe)₃Al₂(SiO₄)₃
Spessartine- Mn₃Al₂(SiO₄)₃
Color: All colors
Refractive index: 1.714-1.888
Birefringence: None
Specific gravity: 3.47-4.15
Mohs harness: 6.5-7.5
TREATMENTS
There are a number of processes used to alter the color, apparent clarity, or improve the durability of gems.
SYNTHETICS
Some gemstones have synthetic counterparts that have essentially the same chemical, physical, and optical properties, but are grown by man in a laboratory.
IMITATIONS
Any gem can be imitated—sometimes by manmade materials or by natural materials chosen by man to impersonate a particular gem.
WHY WE LOVE THIS GEMSTONE
1
Gemological Challenge
Figuring out how each new gem garnet fits into the six main mineral species is a challenge for gemologists.
2
Horsetail Inclusions
Horsetail inclusions in green demantoid garnet are one of the few internal features that increase a gem's value.
3
Fire
Due to demantoid garnet's high dispersion, well-cut, fashioned gems display an amazing amount of fire.
QUALITY FACTORS
When deciding which garnet to buy, think of garnets in terms of color.
COLOR
Garnet includes affordable dark red varieties, rare and valuable greens, and many colors 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 jewelry.
CARAT WEIGHT
Garnets can be found in all sizes and weights, although some varieties are rare in large sizes.
GARNET QUALITY FACTORS: THE COMPREHENSIVE GUIDE
RESEARCH
Explore sources, gemological research, and the role of gems in history.
Supharart Sangsawong, Victoria Raynaud, and Vincent Pardieu , Nov 7, 2016
Ziyin Sun, Aaron C. Palke, and Nathan Renfro , Feb 1, 2016
RECOMMENDED READING
Demantoid Garnet: The Legendary Gemstone Aroused from a Century of Sleep
Masashi Furuya
Exotic gems (Volume 2)
Renée Newman
Garnet
John D. Rouse
