Colombia has almost two-thirds of the world's supply of .

Emeralds.

Explanation:

it's predicted that Colombia has around 65% of Emerald Reserve in the world, making it became one of the most valuable goods that contributed to Columbia's economic sector. (Emeralds are around 20 times rarer than diamonds, so the price for same sized emeralds typically much higher than diamonds).

Emeralds contributed for around 2% of Columbia's GDP annually.  This number is extremely high for one single product.

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