World's Largest Diamond?

I just read that a company in South Africa is claiming to have found the largest diamond ever. It is said to be light green in color and about the size of a coconut! The weight is around 7000cts. Most experts who have seen the photo are skeptical of its authenticity. There is a picture here. Up to now, the largest diamond is the Cullinan Diamond. It weighed a measley 3106cts. in the rough.