World's largest flawless diamond could sell for $20m or more

The largest flawless diamond ever to be auctioned is set to go under the hammer in May at Christie's in Geneva. It is expected to sell for a small fortune, because perfect diamonds like this are incredibly rare - and ones of this size are almost unheard of.

So what will it fetch, and how does it compare with the most expensive diamonds ever sold?%VIRTUAL-SkimlinksPromo%