How do you color grade tanzanite ?

We use the Gemological Institute of America’s (GIA) Colored Stone Grading System.

This system evaluates stones based on three key attributes:

COLOR + TONE + SATURATION

1. Hue (color) – The primary color of the gemstone. Red , blue , green etc ?
2. Tone – How light or dark the color appears. Is a deep beer bottle green or a pale green ?  Scale of  1 – 8 
3. Saturation –How strong and pure is the color ? Scale of 2 – 6

To help visualize, think of it like adding ink to a bowl of water:

• The hue is the ink’s color, say purple.
• The tone describes how dark the blue appears—for instance, a very dark, almost black blue would have a high tone.
• The saturation measures how much of the blue is visible in the water. A few drops of ink would result in light blue water (low saturation), whereas a cup of ink would make the water navy blue (high saturation)

For example, water with a few drops of blue ink might be graded as Blue 3/2 (Hue: Blue, Tone: 3, Saturation: 2).  On the other hand, water with a cup of ink would be Blue 6/7 (Hue: Blue, Tone: 6, Saturation: 7).

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Finally – one more thing..

Due to its unique crystal structure, tanzanite is one of only two known gemstones to clearly show two colors at once. As a result, a tanzanite can never be purely blue or purely violet.

• vB “ violetish- Blue” means that the tanzanite’s dominant color is Blue, and the secondary color is Violet.
• bV “blueish Violet” means that the gemstone’s dominant color is Violet.Want to know more ? here’s an article that  explains the process in more detail: VB 6/6 Tanzanite Color Grading Process

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