I have been looking at the inter net for statements about tourmaline. I would say that a large percentage of the serious pages that make statements about tourmaline are incomplete or wrong in my opinion. I will list simple facts about tourmaline below. To obtain a fuller story please look threw my site or Gemology On Line where I do most of my writing to try and reach a wider audience.
1, Tourmaline can come in all color/hues.
2, Paraiba tourmaline is now define and limited to cuprian tourmaline that contains both manganese and copper in a limited color range. Green to purplish blue.
3, Paraiba should not have a poor tone level, but this not being followed by the trade.
4, Cuprian tourmaline can come from anywhere in the world and any color. It only needs to be colored by copper.
5, Paraiba type was suppose to be used for material that can not be separated from Brazilian tourmaline by eye, but the trade has dropped the ‘type” from the label.
6, Indicolite is a trade name and its color must be dominated by blue and it does not have to be dark or dichroic.
7, Bright yellow tourmaline which is called canary is not colored by magnesium.
8, Radiation can form color centers without any detectable chemical change except for the production of color.
9. Dravite is a metamorphic type of tourmaline and does not come from pegmatites.
10. Long straight inclusion in tourmaline are called growth tubes and are always parallel to the principle axis.
11, Bi-color and watermelon tourmaline that have both green and pink in it always have a thin band of almost colorless tourmaline.
12, Parti colored tourmaline has three or more colors.
13 Bi-color is for tourmaline with two colors.
14 Hi quality Paraiba tourmaline is too expensive to be called semi precious.
15 Tourmaline can be very bright when well polished. (Has high enough index of refraction)
16, Well cut tourmaline is a wonderful natural gemstone. Try it you will love it.
Bruce
