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So the cut significantly influences the color, which determines the price.Cutting a stone to emphasize the blue may waste more of the rough, but because this color is more valuable than violet, the cutter may choose a small fine-colored blue gem over a larger violet one.
Because tanzanite is only found within a few square miles in Tanzania, its price and availability can fluctuate sharply, depending what happens there.
An estimated two million carats of tanzanite were mined before the Tanzanian government nationalized the mines in 1971.
The government divided the mines into four sections, or blocks, in 1990.
Trace amounts of vanadium, mixed with extreme heat, cause the blue color – which ranges from pale blue to intense ultramarine with violet undertones.
Due to pleochroism, tanzanite can display different colors when viewed from different angles.