One of the rarest blues on the planet.
This gemstone can be unearthed in array of many different colours, its name is actually arrived from “turmali” which means “mixed precious stones” in Sinhalese. One of the rarest colours for this incredibly special gemstone, a stone that has great transparency even when its saturation of colour is strong, is blue.
There are three tones of blue Tourmaline. The lighter blue is normally referred to as Paraiba Tourmaline, however when mined outside of the Brazilian state of Paraiba the name should only be applied if the gem has the presence of both copper and manganese elements. The tone of Paraiba is around 25 to 35%, which is normally just slightly darker than say a Sky Blue Topaz.
The darker shade of blue Tourmaline is known as Indicolite. Although occasionally it can be found similar to London Blue Topaz, most pieces I have seen are even darker still. The problem with Indicolite is that you often have to really study the piece to find the blue hues; in all but the best lighting conditions it will appear almost black. When you do see a piece that has a dark rich colour, yet light enough to be open, if it has good clarity and is over one carat in weight, it can sometimes demand as much as £1000 per carat in the trade. If the piece has a dark hue approaching 90% or more, the gem is most likely to be sold to a loose gem collector rather than being set into jewellery.
Sitting nicely between the Paraiba and Indicolite colours is Blue Tourmaline. This tone is normally somewhere between a Swiss Blue Topaz and a London Blue Topaz. Its hue is rarely pure blue and there is normally a secondary hue of green present. This cocktail of colour is truly beautiful. The colour is much more open than Indicolite and whilst the gem looks very pretty indoors, in direct sunlight its appearance transcends from pretty to breathtaking.
Blue Tourmaline is most definitely an outdoor kind of gemstone! Indoors its green hues become more evident and the gem tends to close up and lose some of its transparency. In direct candescent sunlight its blue hues will dominate, its colour opens-up and its appearance is simply world-class.
Over the years I have been fortunate enough to see a handful of Blue Tourmalines and on a recent trip to Brazil I secured a small parcel of wonderful pieces, with text book colour and once faceted they looked truly remarkable. Unfortunately the Cruzeiro Mine near the village of Sâo José Da Safira from where they were unearthed yields very small quantities each year. If the yield was higher then I truly believe the gem would become more famous than Tanzanite, however the rarity of Blue Tourmaline means that it is exclusively reserved for the true gem collector and enthusiast.
World renowned lapidarist Glenn Lehrer once explained to me that getting your orientation right, when cutting a Blue Tourmaline is crucial. If you cut the gem along the C axis you will end up with a gem that has a more pure blue hue and the percentage of green will be minimised, however the gem will appear a lot darker in tone. However, if you orientate the gem such that the A/B axis is table up, the tone will be lighter but the colour will be more of a greenish blue colour. Therefore whether a gem looks more like a Blue Tourmaline or an Indicolite, often will depend on how the lapidarist decided to orientate the gem and therefore maybe other gem experts are after all correct by just referring to all intensely coloured Blue Tourmalines as Indicolite.