When you think of garnets, a dark, richly-hued red stone comes to mind. You may not know that garnets come in a variety of other colors as well, and some are very rare and valuable, like the green demantoid garnet. The name "garnet" comes from the Latin word Garanatus, which means “seedlike,” because the garnets look like pomegranate seeds. Keep reading to learn more about types of garnet and the varying factors that impact the color of this unique and beautiful gemstone.
Gemstone color is an important factor, and they're graded on three factors: hue, tone, and saturation. Hue refers to the gradation of the color, such as light or dark. Tone means the degree of absorption and reflection of light, and it determines the intensity of the stone's color. For example, a dark stone absorbs the light and doesn't reflect light, while a lighter stone reflects more light. Lastly, saturation refers to the intensity of the gemstone's color.
For garnets, the deep red hued garnets are the most popular and abundant. However, you can find stones available in other colors (orange, brown, yellow, pink, green, blue, and colorless). Additionally, rare garnet colors include peach, green, colorless, and blue.
Before we discuss garnet color variations, it's helpful to know that there are two groups of garnets: garnets of calcium and garnets of magnesium. Within these two groups, there are six different types: almandine, pyrope, spessartite, grossular, andradite, and uvarovite. Each of these types is known for having a unique color.
- Almandine: This type of garnet has aluminum silicate to give it a deep red color with a violet tint.
- Pyrope: This is an abundant type of garnet that occurs in colors ranging from purplish-red to dark, blood-red. It's a magnesium or calcium aluminum silicate, and because it's more common than other types of garnet, it is relatively inexpensive.
- Rhodolite: This well-known garnet is a rose-red or purple-red hue. It's often free from flaws and inclusions visible to the naked eye.
- Spessartite: This type of garnet has varying colors that range from fiery orange to reddish-brown that looks like cinnamon.
- Grossularite: This type of garnet is a blend of aluminum and calcium, and has three subcategories:
- Tsavorite: A valuable type of garnet with a green or an emerald green hue.
- Hydrogrossular: Opaque and greenish
- Leuco: A colorless version of this type
Hue Tone & Saturation
Garnets are known for their dense, saturated hues. Hue is the stone's color on the color wheel spectrum - a visual representation of primary, secondary, and tertiary colors. What's unique about garnets is their variety of color from colorless to orange to green to dark red. You can find garnet's colors all over the color wheel.
Garnets also vary in saturation depending on the hue of the stone. Because different types of garnets come in a variety of colors, the saturation varies as well. Every garnet is unique, so examine the hue and saturation of each garnet you come across.
Garnets are known for their color, but their clarity is also important - especially if the stone is lighter colored. Before we discuss opacity, it's helpful to know that there are two groups of garnets: garnets of calcium and garnets of magnesium. Within these two groups, there are six different categories: almandine, pyrope, spessartite, grossular, andradite, and uvarovite. Typical garnet clarity depends on its type. For example, the red garnets almandine, pyrope, and rhodolite typically do not have inclusions visible to the naked eye. Some of the orange garnets, like spessartite and hessonite (a grossular garnet), often have eye-visible inclusions. Rutile inclusions that look like needles within the stone, and are a common type of inclusion in garnets. Additionally, some inclusions give garnets some unique characteristics:
- Hessonite: unique toffee-colored streaks that give it an oily or glass-like look
- Grossular: dark gray to black inclusions
- Star almandine: rutile inclusions can reflect light to give this stone a star-like shape on the stone's surface
Most garnets do not undergo treatment, which is rare for gemstones. Most gemstones are treated in some form to enhance color or clarity. However, garnets are not affected at all by heat or by irradiation, so they are not treated. The one exception is the rare, valuable demantoid garnet, which is green. Sometimes this type of garnet gets heat treated to enhance its green color.
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