Well I can only tell you that Silver Cologne is just amazing. The Crystal has been discontinued. It was recently still available at Bergdorf Goodman in NYC. You need to give them a call if you want to check. You can find decants of the Crystal here or on E-Bay and sometimes a full bottle of the Crystal on E-Bay too.
I understand the Crystal is a deeper, richer, even longer lasting version....if that is possible. I'm sure some owners will chime in here. The Silver Cologne is amazingly deep and lasting and to me, it's the equivalent of an EdP strength from a lot of other houses. Don't let the name "Cologne" fool you. :-) That said, I'd still love to get some of the Crystal too.