Green Gemstones - Tourmaline

Green gemstones is as good a place to begin as any.

Tourmaline: This mineral comes in the most color of any gemstone. The green tourmalines [verdelite] (Let's see some!) colors range from blue with a hint of green to nearly yellow stones. It can come in shades that nearly match peridot (see top image) to chrome greens (Click to view a few!) that rival fine emeralds (by the way chromium is an important coloring agent making corundum red for rubies and beryl green for emeralds - more on this later...).

Tourmaline is often strongly dichroic (showing two distinct color axis); thus when you are examining a stone you will note one color when looking down the table and another color looking in from an end (faceting tends to blend the colors). Tourmaline is an excellent mineral for faceting: it cuts easily, with no obvious cleavage, and takes an great polish. It is one of my favorites for cutting, particularly the material from Afghanistan with its open c-axis and its midtone of colors (not to dark, not to light). This gemstone has good brilliance and reasonable hardness making it great for jewelry.

Tourmaline usually forms in long, triangular crystals (take a look) (the shape makes it good for faceting, less waste; see second image down); although Uvite tourmaline is an exception to the shape. Bicolors are relatively common: green to blue and green to red (step cuts are better for these stones as they mix the colors less than brilliant cuts). Tourmalines can also form "watermelon" material where a red core has a green outer layer, this material is usually cut perpendicular to the long c-axis and polished to highlight the effect. An interesting and unusual effect is when the green stone has long red veils running down the center of the stone, this looks like an Mercedes Benz hood ornament (see bottom image).