1, red-pink tourmaline
Red to pink due to manganese, pleochroism is obvious, red to pink. The most valuable is the tourmaline called “double peach†in the business world.
2, blue tourmaline
Due to the blue color of iron, the pleochroism is from weak to weak, showing dark blue and light blue.
3, green tourmaline
It is green due to its chromium and vanadium elements, and its pleochroism is obvious. It is light green and dark green. The birefringence is high, usually 0.018, and the highest is 0.039.
4, brown tourmaline
Mostly magnesium tourmaline, versatile, dark brown to green brown.
5, two-color tourmaline
A ribbon (two-color, three-color, and multi-color) that is often distributed along the long axis of the crystal, or a ribbon that is concentrically distributed, usually called "watermelon tourmaline" when the inner infrared is green.
Solid French Terry,Soft Recycled Cotton French Fabric,Solid Terry Knit Fabric,Printing French Terry Fabric
Shaoxing Huangdaopo Trade Co.,Ltd. , https://www.sxhdptrading.com