Gems of the tourmaline family have the greatest range of colors of any gemstone and individual crystals may be color-zoned both from the inside out and from the bottom to top. This is a consequence of the chemical composition of minerals of the tourmaline group whose crystalline structures readily permit one metal ion to replace another. Names used for such crystals include, bi-colored tourmaline, parti-colored tourmaline, "party colored" tourmaline, and watermelon tourmaline.
Among the most attractive East African tourmalines are the greens colored by vanadium and chromium from Tanzania and Kenya and the electric blues and purples from Mozambique, colored by copper and manganese.
We also occasionally see red tourmaline colored by manganese, blues with iron as the coloring agent, canary-yellow titanium-bearing tourmalines, and other shades of green in which the color effect of a tiny amount of chromium has been naturally enhanced by the presence of magnesium. So far we have never seen an orange tourmaline, but who knows what the future may bring.

Our African Paraiba tourmalines

Paraiba tourmalines have become quite a subject of conversation in the past couple of years. Paraibas (or as they should probably be called for the time being “African Paraiba tourmalines”) have recently been discovered in a couple of African countries (Mozambique and Nigeria).

Since Swala Gem Traders has opened up a purchasing office in Northern Mozambique early 2007, we have been purchasing a few selected Paraibas. These Paraiba tourmalines are quite exceptional and sometimes have different characteristics than the ones from Brazil. They are usually much cleaner and much bigger. They probably need less often heating and display colors than are not always similar (more purples, in general not quite as flashy).

Chemistry:
System: Trigonal
Hardness: 7-7.5
Density: 3.06
Ref. Index: 1.624(+.005, -.005) - 1.644(+.006, -.006)
Birefringence:
Pleochroism: dichroic

On internet:
Paraiba tourmaline on the ICA website
La tourmaline paraiba sur le site de l'ICA
View paraiba tourmaline on mindat.org

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