10 Sep Spessartine Garnet Guide
Spessartine is a variety of garnet distinguished by its vivid orange fire.
The most desired stones are pure vivid orange and you will sometimes find them described as “fanta” or “mandarine” garnets.Same as with other garnets, there are a lot of stones that contain molecules appropriate to a different garnet species. As a result there are many stones with a varying degree of red hue present, due to the Almadine molecule. More rarely you will also see gemstones of this species that depart towards the yellow.
The unusually strong brilliance, exceeded only by diamonds, zircons and andradites is surely one of the main reasons why this gem has gained popularity so quickly. Spessartine garnet burns brightly even in a subdued light and its vivid orange is among most attention-catching colours. If you look for a jewel that will attract with its colour and sparkle, spessartine is a good choice for you. Especially if you plan on using yellow gold for your design. The name that is known in US as spessartite comes from the German “Spessart”, an area in Bavaria where it was first discovered. Currently Nigeria, Madagascar and Sri Lanka are the main suppliers but there are other localities producing varying amounts.
Before 1990’s spessartines were mostly collector stones, mined in Virginia and California.
In 1991; however, large deposits were discovered in Namibia and this gem could finally enter a wide retail market. Following the Namibian find there was a significant new source discovered in 1999 in Nigeria. It produced an even greater amount of a good clarity material. You should bear in mind that deposits of this gem can be exhausted pretty quickly. Like it happened to the Namibian source which was depleted in just a couple of years. This results in a marketplace that gets periodically saturated but it may not be the case forever. There’s always a possibility this gem may go back into the rare collector status again. The fluctuating availability of spessartine is connected to its occurrence and formation.
The main sources of spessartine garnets are veins of pegmatites.
A granite type of rock resulting from hot magma intruding into other types of already solidified rock.To find spessartine garnet we have to find these veins first but it is not enough. We also need to find the ones, that have a sufficient level of manganese element present as that’s what’s responsible the rich orange colour. As is the case with many gemstones, these garnets are sometimes also found in alluvial deposits of ancient rivers. Washed out of their host rock and transported downstream to be deposited again in layers of an ancient mud. Spessartines are normally not heavily included, so obtaining reasonably clean stones isn’t hard. Still a fine quality gems over the size of 5ct are fairly rare. The exception from the usual clarity rules are Namibian stones. They often contain fibrous inclusions of tirodite which gives them “sugary” look. It is not viewed as a flaw as it disperses the light inside of a gem, countering the extinction. In effect, spessartines that contain it appear more brilliant. In case of Namibian stones, everything over 1-2ct is considered rare and over 5ct is scarce.
Garnets belong to the cubic crystal system and do not display pleochroism. Their colour is exactly the same from every direction.
This in turn allows crystals to be cut at any orientation, giving cutters good yields from rough material. An additional effect of that is a broad range of shapes available- rounds, ovals are most popular but cushions, hearts and pears are available too. In that respect, spessartine is unlike many other stones that must be cut at certain orientation to display prime colour. Which usually results in a narrow range of traditional shapes limited by the crystal shapes. Although, not as hard as spinels, rubies, sapphires or diamonds, spessartines are quite durable at 7.25 on Mohs scale. They should cause no trouble with a daily use, unless subjected to a rough treatment. While wearing them, you should avoid manual labour, sport or other activities that may result in significant abrasion or knocks.
To clean your gems I recommend a warm soapy water and a soft brush.
Ultrasonic cleaners should be safe, if there are no liquid inclusions present but do not use steam cleaners as sudden, large temperature changes may shatter your garnet. Thankfully there are no synthetic Spessartines currently on the market, probably due to the complicated chemistry of the garnet family. Neither are treatments currently being used on these gems, although there’s still a possibility of imitations, with two most common being a glass and hessonite garnet.
To learn more about Pegmatites go to Wikipedia http://en.wikipedia.org/wiki/Pegmatite