What are the most-valuable diamonds to buy?

Diamond jewellery sales have been booming, with sales up a whopping 10.5% this year, according to Gemmological Data.

But some sellers say the demand for the metal is high, with buyers often finding the diamonds at auction.

The value of diamonds in the US has jumped from $1,300 per tonne to $1.3 million.

It is estimated that more than 100 million tonnes of diamonds are made each year in the United States.