The Regent diamond, a 410 carat stone (about 1/5 of a pound), was discovered in 1698 by a slave in the Golkonda mine in India. The slave, who recognized the potential value of the Regent diamond, stole the precious stone and hid it inside of a large wound in his leg; however, an English sea captain witnessed this and subsequently stole the diamond from the slave. The Englishman then sold the diamond to an Indian merchant, who in turn sold it to Governor Thomas Pitt for what today would be almost $6 million USD.
The Regent diamond, sometimes referred to as the Pitt diamond, belonged to French royalty for many years, even serving as an adornment in the hat of Marie Antoinette. This diamond is now on display in the French Royal Treasury at the Louvre Museum in Paris.
Also take a look at some other Famous Diamonds:
The Hope Diamond
The Cullinan Diamond
The Centenary Diamond
The Koh-I-Nur Diamond
The Orlov Diamond