1. Blue Diamonds
Price per CD: $4,028,940
Finally, blue diamonds are among the rarest of diamonds, so no wonder they are also the most expensive gemstones in the world. As seen before, colored diamonds are much rarer than colorless ones, but the blue ones are at the top. Since Diamonds are made only of carbon, the blue tone in these diamonds comes from Boron inclusions. There are only several mines where blue diamonds come from: Cullinan in South Africa, Argyle in Australia and Golconda in India.
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