How Much Is 20 Carats of diamond worth?

Anything is 'worth' what someone will pay you for it.

Carat weight is only one of four parameters used to value diamonds. The others are cut, colour and clarity.

A single twenty-carat diamond will be worth more than many diamonds that make up a total carat weight of 20 carats.

Every diamond is valued individually, depending on the four Cs used to value diamonds, as above.