Genoa paid Juve 12.5m euro for Criscito (1m for the loan in 2008/09, 5.5 for co-ownership in 2009/2010 and 6m for the other 50% in 2010/2011) and now they're selling 50% of his contract for 6m eur.
Looks like the boy didn't add much to his price with his performances for Genoa. Quite the contrary.