All these garnets are members of the isomorphous Pyralspite series of garnets (along with spessartite) with red to purple hues. Pyrope has a blood-red color with few inclusions. Almandine garnet, or almandite garnet, is deep red to violet and can show asterism.
Magnificent Pyrope/Almandine garnets, the color of fine French Claret wine, come from Mozambique and are known as "Mozambique Garnet." These have become highly prized when they look very beautiful.
Rhodolite garnet is a combination of pyrope and almandine. It's a red to reddish-pink or violet gemstone sometimes called ‘grape garnet’. This is one of the superior varieties of pyralspite garnet as it is far brighter.
These gems' colors are deep blood-red to red, reddish-pink, and violet. The division between pyrope and almandine is somewhat arbitrary, so many garnets are called pyrope almandine!
Image: Rhodolite garnet
Mohs Hardness: 7-7.5
Luster: Vitreous (glassy)
Specific Gravity: Pyrope: 3.62-3.87; Almandine: 3.93-4.30; Rhodolite: 3.74-3.94
Refractive Index: Pyrope: 1.72 – 1.76; Almandine: 1.77-1.82; Rhodolite: 1.74-1.78
Chemical Formulas: [Mg,Fe,Mn]3Al2(SiO4)3 | Pyrope: Mg3AL2(SiO4)3; Almandine: Fe3Al2Si3O12; Rhodolite: (Mg,Fe)3Al2(SiO4)3
Image: Rhodolite garnet ring
All garnets crystalize in the cubic (isometric) system. Symmetrically, crystals are in cubes, octahedrons, or pentagonal dodecahedrons, though spherical crystals also exist.
Niassa National Reserve, Cuamba mine, Mozambique, (Mozambique Garent) Umba River Valley, Tanzania (Rhodolite)
Image: Mozambique grape garnet with SI (Slightly Included) clarity
As with all colored gemstone grading, the 4C’s apply. Small, dark garnets are very cheap. When the size gets larger, the value increases enormously – if the stone is eye-clean (lacks visible inclusions).
Mozambique garnets, especially rhodolite garnet, are a good investment as they are very similar to rubellite tourmalines. In the past year, they have increased in price as the tourmalines have, but not at the same level – yet! Large rhodolite garnets are gaining some notoriety and considerable collectability.
Garnets are greatly underrated. We are big fans of all things garnet, and we specialise in gems and beads. These gems are going up in price, along with all gemstones, but they're a worthy investment. If someone puts a large pink rhodolite in front of me, I will have to hide my delight as I haggle!
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