GIA Tanzanite Color Grades: Understanding “VB 6/6”
October 8, 2024 3:49 amHow the GIA Colored Stone Grading System Works
The GIA grading system evaluates gem color based on three components:
- Hue: This reflects the basic colors we perceive. When discussing a gem’s “color,” most people refer to its hue.
- Tone: This indicates a gem’s relative lightness or darkness on a scale from 2 to 8.
- Saturation: This describes the hue’s intensity on a scale from 1 to 6.
In gemological reports, gemologists use abbreviations, capitalizing the primary color while using lowercase for secondary colors. For example, “vB” stands for violetish blue, and “bV” indicates bluish violet.
For instance, a tanzanite graded as “vB 6/6” means:
- Hue: Violetish-Blue (vB) – Blue dominant, violet secondary
- Tone: 6 – Medium Dark
- Saturation: 6 – Vivid
Important Facts
It’s important to note that the GIA does not issue Gemological Reports stating a tanzanite’s color grade.
Tanzanite is graded under white light. It WILL change color under different lights – and some stones can be very “moody” or exhibit very different colors in different lights.
Buyer Beware! Expecting to find an intensely saturated blue tanzanite weighing less than 2.50 carats can lead to disappointment. A fine, 1.00-carat tanzanite is likely to be at most a medium blue, or GIA 5/5. Consumers should be cautious of online retailers selling smaller stones (between 0.50 and 2.50 carats) as “investment grade” or GIA 6/6.