Tanzanite · Origin
Block D, Merelani Tanzanite
Block D is the specific mining block within the Merelani deposit most associated in the trade with producing the largest and most richly colored tanzanite ever recovered.
Historic finds from Block D have included some of the largest and finest tanzanite crystals on record, which is why "D-block quality" has become trade shorthand for top color saturation even when describing stones from elsewhere in the deposit. It illustrates that, within a single-origin gemstone, mining block and color grade can matter as much as country of origin does for other stones.
See how origin fits into overall value in our Tanzanite buying guide and Tanzanite price guide, or verify a specific certificate on our Tanzanite certification page.
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