Mandarin Garnet Matched Pair Natural Genuine Gemstone,GRG,485

Today’s Item is matched pair of natural Genuine Round faceted Gemstones of Mandarin Garnet 5 mm each. these Mandarin Garnets are rare to find in this color and clarity in this type of gemstones, as it has the orange color.

Gemstone size is 5 mm
Ct weight 1.61 KT

Attributes

Origin Nigeria, Sri Lanka, Ceylon, Madagascar, Brazil, Sweden, Australia, Myanmar, Burma, U.S.A
Color Orange, yellowish orange, reddish orange, orange-red
Refractive Index 1.79-1.81
Chemical Composition Mn3Al2(SiO4)3
Hardness 7.25
Density 4.14-4.20
Crystal Structure Cubic
There are two main theoretical groups or families of garnet: pyrope, almandite, spessartite, which are all (metal) aluminum silicates, and uvarovite, grossularite, andradite, which are all calcium (metal) silicates. In practice, there are probably very few garnets with the precise pure chemical composition shown for their type, almost all garnets are of mixed types, where one type is partially replaced by another type.

Garnets as a group are relatively common in highly metamorphosed rocks and in some igneous formations. They form under the high temperatures and/or pressures that those types of rocks must endure. Garnets can be used by geologists as a gauge of how much temperature and pressure the rock has endured. Garnets are greatly variable in colors and varieties, though, and many of these are both rare and beautiful, producing genuinely precious gemstones. Some garnets are truly unique in the mineral kingdom and have much to offer as both gemstones and mineral specimens.

The general formula for most of the garnets is A3B2(SiO4)3. The A represents divalent metals such as calcium, iron, magnesium and/or manganese. The B represents trivalent metals such as aluminum, chromium, iron and/or manganese and in the rarer garnets; vanadium, titanium, zirconium and/or silicon. The general formula for a couple of rarer garnets (hibschite and katoite) is A3B2(SiO4)3-X(OH)4X. The main differences in physical properties among the members of the garnet group are slight variations in color, density and index of refraction.

Most gems have a crystalline structure. Crystals have planes of symmetry and are divided into seven symmetry systems. The number of axes, their length, and their angle to each other determine the system to which a crystal belongs. Garnets are isostructural, meaning that they share the same crystal structure. This leads to similar crystal shapes and properties. Garnets belong to the isometric crystal class, which produces very symmetrical, cube-based crystals. The most common crystal shape for garnets however is the rhombic dodecahedron, a twelve sided crystal with diamond-shaped (rhombic) faces. This basic shape is the trademark of garnets, for no other crystal shape is so closely associated with a single mineral group like the rhombic dodecahedron is with garnets.

Most garnets are red in color, leading to the erroneous belief that all garnets are red. In fact a few varieties, such as grossularite, can have a wide range of colors, and uvarovite is always a bright green. As a mineral specimen, garnets usually have well shaped and complex crystals and their color and luster can make for a very beautiful addition to a collection.

What makes Spessartite Garnets so special?

Besides its wonderful colors, spessartite garnet, has additional advantages which make it a truly unique and valuable gemstone. There is its hardness of 7-7.5, making it perfect for any piece of jewelry. Additionally these gemstones have a remarkably high refraction of light, giving it an exceptional brilliance. Even in unfavorable lighting conditions small, well cut Mandarin garnets will sparkle brilliantly. The refractive index (RI), measured using a refractometer, is an indication of the amount light rays are bent by a mineral. Birefringence is the difference between the minimum and maximum RI. When birefringence is high, light rays reflect off different parts of the back of a stone causing an apparent doubling of the back facets when viewed through the front facet. Spessartite garnet is singly refractive and thus has no birefringence.

Color

Spessartite Garnet is idiochromatic, meaning that it is colored by a fundamental element in its composition. That element is manganese, which produces an orange color. Take away the manganese, and it would no longer be spessartite. Thus spessartite has only one basic color – orange. That said, the color may be modified slightly by mixing with iron, in the form of almandine. This produces a deeper, more reddish coloration. Spessartite Garnet can be found in all the ranges of orange from the color of ripe peaches to a deep orange-red. The most valuable spessartite are a bright, slightly reddish orange.

Cut

Spessartite are generally cut similar to other colored stones, with ovals, cushions, trillions and emerald cuts being most common. Other popular mandarin garnet shapes include rounds, marquises, briolette’s, hearts and pears. The lack of pleochroism means that orientation is not a problem and the equidimensional shape of the rough generally provides good yields from rough to cut. Cabochon-cut spessartite are also seen on occasion, particularly with the Namibian mandarin spessartite, which tend to be more heavily included.

Treatments
Spessartite are not currently enhanced by any method.

Sources

Gem spessartite has been found at a number of localities around the world, including Brazil, Burma, Madagascar, Mozambique, Namibia, Nigeria, Sri Lanka and the USA (San Diego County, CA and Amelia Court House, VA). Of these sources, the most important today are Nigeria and northeast Namibia, in the vicinity of the Marine fuss River.

Africa

The discovery of the iron-free, brilliant orange spessartite garnet in Namibia in 1991, in commercial quantities created a sensation in the jewelry trade. The deposit lay in mica schist along the course of the Kunene river in the mountainous northwest area bordering Angola. Few inclusions marred the excellent crystals. The name hollandite was chosen for its introduction as a spectacular new gemstone. This was changed to Mandarin garnet when it was discovered that hollandite denotes a little-known metal. Within less than five years time, the deposit was depleted, and the area closed. The planned recovery of material from metamorphic bedrock in the rugged terrain surrounding the first find will be more difficult. Crystals recovered from the surface layer of this area contain numerous inclusions of tremolite, but cleaner material lies below. In 1999, a new source was discovered in a remote area of Nigeria. Though the material was more yellow than the orange Namibian crystals, the size and abundance of the material made the public more aware of and increased the demand for spessartite gems. Despite great expectations, this deposit, too, was quickly depleted. Acquisition of material from the Nigerian area is sporadic and available only in small amounts from local native traders. Currently, developers are investigating a promising new deposit of a high (reputedly 90% or more) manganese content material located in the gem-rich Alto Mirador pegmatite dike of Paraiba in Brazil.

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