Ann: Exceptional 104 Carat Diamond Recovered at Lulo-LOM.AX, page-3

Taken from the interwebs.

"Of all the diamond types, type IIa diamonds are the most rare valuable and therefore, the most sought-after by collectors and investors. In fact, this type represents just 1 percent of all diamonds, so they are highly valuable and obviously a superior choice for investment. The reason why these stones are so exceptional is that they contain very little nitrogen or none at all within the crystal lattice, so they do not easily absorb short-wave light.
The result is that light is easily able to pass through and bounce back at the beholder's eye, producing a stunning appearance. Because they are almost pure carbon, white diamonds are remarkably colorless"

To summarize, this is one expensive stone!