How Big and Green is my Emerald?

Most GMs use gems and jewels in their games but just how big can they get?  From the ABC News site, and according to Western Star Auctions, "What is said to be the 'world's largest emerald' is 12 inches long and weighs 11.5 kilograms. It was appraised at $1.15 million because it is a rough cut stone."  And, it will be auctioned on Jan. 28 at Western Star Auctions in British Columbia, Canada, so get in line!