What is the most expensive stone in the world?

Valuation of diamond is determined by the gem quality: carat weight, clarity, color, uniqueness as antique, or one of its kind in this world.

Collectors value a diamond with demand: for a unique diamond the cost is priceless. A 100 carat diamond sold for $ 24.3 million in 1995. The star of Africa (Cullinan diamond) is 3,106 carats and worth many times other expensive diamonds sold.

Most of the world's largest, most glorious diamonds have never traded hands for money, rather, are gifts or spoils of war.