The defender had previously been playing for the Genoa side, whilst being jointly owned by Parma.
Diana's transfer is the second high profile departure of the week for Parma, following Adriano's big-money switch to Internazionale.
The Serie A giants have officially announced that they now enjoy complete ownership of the Brazilian, who was rumoured to be interesting Chelsea.
The highly-rated forward has signed a contract that will expire in 2008, with cash-strapped Parma set to receive up to ‚é¼20 million, plus Isah Eliakwu and Ianis Zicu.
