garnet , pyrope , almandine
| Mineral information | Garnet |
| Chemical composition | X3Y2Si3O12 |
| _ The Mineral and Gemstone Kingdom |
Help | Pictures |
| Color | Red, reddish-brown, brown, green, yellow, orange, pink, purplish-red, white, colorless, black (Garnet occurs in every color except for blue) |
| Hardness | 6½ - 8½ |
| SG | 3.5 - 4.3 |
| RI | 1.780 - 1.889 |
| DR | None |
| Luster | Pyrope, Almandine, Spessartine, and
Grossular have a vitreous luster Andradite (including Demantoid) and Uvarovite have an adamantine luster |
Garnets are often thought of as dark red gems. Garnets, however, have a
great color variation, and gems of all colors (except blue) are cut from them. Garnet is
not a single mineral, but a group of minerals closely related in physical and chemical
properties. The individual minerals of the garnet group are called "garnets" The
six types of garnet used as gems are:
Pyrope
Almandine
Spessartine
Grossular
Andradite
Uvarovite
Each type is discussed in detail:
Mineral information Pyrope Chemical composition Mg3Al2Si3O12 Color Deep red to nearly black; rose-red to violet Hardness 6½ - 7½ SG 3.5 - 3.6 RI 1.780 - 1.810
Pyrope is the most famous form of garnet. Its dark, blood-red color is distinct and attractive. Pyrope gemstones are often totally clean of inclusions. A rose-red to violet variety, known as rhodolite, is also a popular gem. Rhodolite is not a pure variety of pyrope, but a mixture of pyrope and almandine.
SYNONYMS
Many deceitful names are given to pyrope garnet in connotation with ruby. These names are used by unscrupulous dealers to confuse inexperienced buyers:
Adelaide Ruby
Mineral information Almandine Chemical composition Fe3Al2Si3O12 Color Deep red to reddish-brown, sometimes with a violet or brown hue Hardness 6½ - 8½ SG 4.3 RI 1.730 - 1.760 Almandine is the most common garnet, and the most widely used garnet gem. It is usually black and opaque, but lighter colored stones are occasionally found. Most almandine is too dark to use as a gem. The underside of some gems are hollowed out to let more light enter the stone, thus giving the gem a lighter color. If the bottom of the garnet is covered by a jewelry setting, the only way to easily determine if the garnet is hollow is by its lighter weight. Almandine garnets are usually faceted with the brilliant cut, which fully displays the fiery red color of this gem. Very dark or heavily included almandine garnets are cut and polished into cabochons, and asterism (in the form of a four rayed "star") is observable in almandine garnets from certain localities.
SYNONYMS
Mineral information Spessartine Chemical composition Mn3Al2Si3O12 Color Brown, orange, pink, brownish-red Hardness 7 SG 4.2 RI 1.795 - 1.815 Natural spessartine has an orange color, but iron impurities are usually present, giving it a reddish or brownish color. Spessartine itself is not a common garnet, and is usually not found as transparent, gem quality material. Orange, pink, and brownish-red gems and cabochons are cut from this garnet. Spessartine is one of the lesser-known garnets, as it does not have any superior attributes over the other garnets (and it is rather uncommon). A purplish-red to violet garnet, known as grape garnet, is an intermediary between spessartine and almandine. A new find was recently discovered in India, sparking new interest in this rare, purplish form of garnet.
SYNONYMS
Mineral information Grossular Chemical composition Ca3Al2Si3O12 Color Colorless, white, green, yellow, pink, brown, orange, orange-red. Massive grossular garnet may be multicolored white, light green, and pink. Hardness 6½ - 7½ SG 3.6 RI 1.738 - 1.745 Grossular is the most varicolored garnets. Pure grossular, without any impurities, is colorless; the wide range of colors in this garnet is caused by various impurities. Many of the varieties have distinct names, some of which are used in jewelry:
Grossular garnet is cut into various gems, with the varieties hessonite (orange) and tsavorite (green) being the most popular. The pink form of this gem is occasionally cut into gems, but all other colors are rarely used. Grossular garnet also has another gem form, that, like jade, is used in carvings and sculptures. This massive, compact variety is usually called South African Jade or Transvaal Jade. Other names for this material are African Jade and Garnet Jade. This material is usually green, but is sometimes multicolored pink and green. It was often mistaken for jade in the ancient oriental jade market.SYNONYMS
Mineral information Andradite Chemical composition Ca3Fe3+2Si3O12 Color Green, yellow, orange, reddish-brown, brown, black Hardness 6½ - 7½ SG 3.8 - 3.9 RI 1.888 - 1.889 Andradite is the most lustrous of all garnets, and its dispersion ("fire") exceeds even that of diamond. There are three gem varieties of andradite:
The demantoid variety, which is remarkably rare, is the most valuable form of garnet. The combination of its color and fire give it unsurpassed splendor. Demantoid is easily identified by its characteristic "horsetail" inclusions. Demantoid was very popular in the 19th century, but its popularity has decreased because of its rarity and softness. The variety topazolite rarely occurs in crystals large enough to be worth faceting, and is thus rarely seen in jewelry. The variety melanite was once used in mourning jewelry, but does not have any gem use nowadays.
Mineral information Uvarovite Chemical composition Ca3Cr2Si3O12 Color Emerald-green Hardness 7 - 7½ SG 3.7 - 3.8 RI 1.860 - 1.870 Uvarovite is the rarest of the familiar garnets, and is seldom used as a gem. It only occurs in very small crystals, and a crystal large enough for faceting is usually preserved as a mineral specimen. This garnet is only occasionally faceted for collectors into gems.
SIMILAR
GEMSTONES
Due to the great color variations of garnet, many other
gemstones may be confused with it. In addition, many of the garnets are very similar in
appearance, such as demantoid and tsavorite. Below is a list of gemstones that appear
similar to the garnets:
Red garnet - ruby, spinel, rubellite, and carnelian
Green garnet - emerald, tourmaline, hiddenite,
zircon
Yellow-green garnet - peridot, chrysoberyl,
heliodor, topaz
Orange garnet - topaz, chrysoberyl, golden
beryl, zircon, citrine, spinel
Pink garnet - rose quartz, kunzite, spinel, tourmaline,
topaz, morganite,
pink sapphire
Massive, compact grossular garnet - jade, californite
ALSO SEE
Special thanks to Gem Hut for most of our gem images. The gems displayed or others like them can be purchased through Gem Hut by clicking the link below each picture.
Picture: Red Pyrope Garnet
Size: .25 ct. (both gems)
Cut: Trillion
Gem: Gem Hut
Picture: Blood-red Pyrope Garnet
Size: 3.21 ct.
Cut: Heart
Gem: Gem Hut
Picture: Dark red Almandine Garnet cabochon
Size:
Cut: Cabochon
Gem: Gem Hut
Picture: Reddish-brown Almandine Garnet
Size: 2.34 ct. (both gems)
Cut: Oval
Gem: Gem Hut
Picture: Purplish-red Grape Garnet
Size: 3.70 ct. (both gems)
Cut: Oval
Gem: Gem Hut
Picture: Pink Rhodolite Garnet
Size: .63 ct. (both gems)
Cut: Round
Gem: Gem Hut
Picture: Green Tsavorite Garnet (Grossular)
Size: 1.94 ct.
Cut: Oval
Gem: Gem Hut
Picture: Light pink Imperial Garnet (Grossular)
Size: .96 ct.
Cut: Pear
Gem: Gem Hut
Picture: Bright orange Spessartine Garnet
Size: 5.05 ct.
Cut: Oval
Gem: Gem Hut
Picture: Red Spessartine Garnet
Size: 5.72 ct.
Cut: Pear
Gem: Acme Imports
Picture: Fiery-red Spessartine Garnet
Size: 4.00 ct.
Cut: Pear
Gem: Acme Imports
