GIA Tanzanite Color Grades: “VB 6/6” Tanzanite explained

Gemologists using the GIA Colored Stone Grading Scale will grade fine-colored tanzanite as “GIA 5/6”. Its rich and vibrant color is highly valued and universally appreciated. If you are a connoisseur of fine gems, you’ll probably be most interested in obtaining and owning the rarest grade of tanzanite – often called “investment tanzanite”, which makes up less than 1% of all production and is graded 6/6.

So how does the GIA Colored Stone Grading  System work? It breaks down gem color into three components:

  • Hue – reflects the basic colors we see. When most people discuss a gem’s “color”, they are actually referring to its hue.
  • Tone – refers to a gem’s relative lightness or darkness (on a scale of 2 – 8).
  • Saturation – refers to the hue’s intensity (on a scale of 1 – 6).

When describing gem values in reports, gemologists use abbreviations and capitalize the primary color. Lowercase is used for all other letters. So, “vB” means violetish blue, and “bV” means blueish violet.

For example, a tanzanite graded as “vB 6/6” means:

  • Hue: violetish-Blue / vB –  (Blue dominant, violet secondary)
  • Tone: 6  – ( Medium Dark)
  • Saturation: 6  – (Vivid)


  • FACT: The GIA does not issue Gemological Reports which state a tanzanite’s color grade. Learn more about GIA Tanzanite Reports here…
  • Buyer Beware! You should not expect to find an intensely saturated blue tanzanite weighing less than 2.50 carats. The color of a fine, 1.00 carat tanzanite is likely – at absolute darkest – to be a medium blue or GIA 5/5. Consumers should be wary of online retailers selling smaller stones (between 0.50 to 2.50 carats) as “investment grade” or GIA 6/6.
  • Learn more about the GIA Color Grading Process…