Color

• When purchasing green tourmaline for a ring, the color of the stone plays a significant role in the ring's value. Green tourmaline can range from very pale green to blue-green to brownish-green. Stones that are blue-green in color to a deep bottle green are the most sought after and expensive.
  
  

Size

• Like all other stones used in jewelry, green tourmaline is measured in carats. An increase in the amount of carats of a stone will increase the cost of the ring.
  
  

Cut

• The cut of the green tourmaline stone used in rings is critical to the value of the ring. Green tourmaline is a particularly difficult stone to cut, especially dark colors of the stone. Making sure the stone is cut parallel to the growth of the main axis is important when buying a tourmaline ring. The proper cut will bring out the brilliance of the green tourmaline ring.