The largest gem-quality diamond ever found was discovered in a South African mine in 1905. The so-called Cullinan diamond weighed 3,106 carats, or about 1-1/3 pounds.

The Transvaal government purchased the stone and offered it to Edward VII on his 66th birthday, but the problem remained how to transport such a valuable object safely to England. Amid great publicity and heavy security, an ocean liner set out carefully for London.

It was carrying a decoy stone — the real diamond was sent by parcel post. It arrived safely.

(Thanks, Ross.)