Spessartite Buying Guide
Garnet is the name for a group of related mineral species. The gem garnets include:
In addition to the purer end members mixed garnets such as malaia (or malaya, a pyrope-spessartite) and grandite (a grossular-andradite mixture) exist. The purplish pyrope-almandine mixture is called rhodolite.
The name spessartite (a.k.a. spessartine) is derived from Spessart, in N.W. Bavaria, Germany.
Spessartite garnet is ideochromatic, 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.
Spessartites occur in three basic flavors. There are the light and bright stones, which come from Nigeria, Ramona (CA) and the deeper reddish orange stones that also come from Nigeria. Then there are the fabulous tangerine orange “mandarin” garnets from Namibia, which are in a class all by themselves.
Due to its orange to red-orange color, spessartite generally looks best under incandescent light. When buying any gem, it is always a good idea to examine it under a variety of light sources, to eliminate future surprises.
Spessartites from most sources are reasonably clean. Thus eye-clean stones are both desirable and possible. The exception is with the mandarin spessartites from Namibia, which often contain small colorless fibers of tirodite that give the stones a sleepy overall appearance. When only small amounts are present, the effect can be quite beautiful, masking extinction and allowing the beautiful tangerine orange color to shine completely across the entire face of the gem.
Spessartites are generally cut similar to other colored stones, with ovals, cushions, trillions and emerald cuts being most common. 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 spessartites are also seen on occasion, particularly with the Namibian mandarin spessartites, which tend to be more heavily included.
The prices of spessartite are, like any gem, dependent on quality. Still, we can make a few generalizations. The flood of Nigerian spessartite took what was once essentially a collector's stone into the realm of jewelry staple. Nigerian spessartites typically retail for $100–250/ct. in the smaller, 1–4 ct. range, while stones of 15–20 cts. may reach as much as $900/ct. at the retail level.
Prices for the rare mandarin spessartites from Namibia are even higher, with smaller goods (1–2 cts.) fetching up to $800/ct. and fine stones above 5 cts. extending well above $1000/ct. The largest fine mandarin garnet seen at Pala was a super 8-ct. stone priced at $2400/ct. retail.
While spessartites of greater than 100 cts. cut are known from both Brazil and Madagascar, fine gems of more than 15–20 cts. are rare. For mandarin garnets from Namibia, fine gems of greater than 5 cts. are scarce.
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 Marienfluss River.
Unlike many colored stones, spessartites are not currently enhanced by any method.
Spessartine has never been synthesized, but a number of imitations exist, including natural stones such as hessonite garnet, and man-made imitations such as glass.
Properities of Spessarite (Spessartine)
|Composition||Spessartite garnet has the following composition:
|Hardness (Mohs)||7 to 7.5|
|Specific Gravity||4.15 (+ 0.05; - 0.03)|
|Refractive Index||1.810 (+ 0.004; - 0.20)|
|Crystal System||Isometric; usually occurs as massive pebbles or dodecahedra/icositetrahedra combinations|
|Colors||Due to its ideochromatic nature, spessartite is always some shade of orange. The color is caused by manganese.|
|Phenomena||Pyrope-spessartite mixed garnets containing vanadium have been found that display a dramatic green (daylight) to red (incandescent light) change of color. Such stones come from East Africa and Sri Lanka.|
|Handling||Ultrasonic: generally safe, but risky if the gem contains liquid inclusions
Steamer: not safe
The best way to care for spessartite is to clean it with warm, soapy water. Avoid exposure to heat or acids.