What is “D block” Tanzanite and is it better than tanzanite mined in the other blocks?

The only tanzanite deposit on our planet barely covers eight square miles, and “D Block” refers to one of the four blocks into which it was divided by the Tanzanian government. Legend has it that D Block is responsible for producing the finest tanzanite. However, the scientific truth is that tanzanite’s quality or value can in no way be guaranteed by its exact location within the deposit.

An aerial view of the world’s only tanzanite deposit, showing D Block and part of C Block.  Exceptional tanzanite gemstones, as well as tanzanite of any other quality, can be found anywhere in this deposit. D block is mined by small artisanal miners ( which is why it looks busier on the surface), while C Block is mined with more modern methods and a series of extensive underground tunnels.

Nevertheless, many online sellers try to capitalize on this legend and use the phrase “D Block” to promote their tanzanite as superior. You should be aware there is no scientific way to tell which block any tanzanite gemstone came from (as it is all one deposit), and, even more importantly, that the block is in no way an indicator of high quality.

“D Block” and ” AAA” tanzanite. These two phrases have absolutely zero scientific basis, but are very commonly used to imply high value and superior quality of tanzanite stones.