Just got this mailed to me, new Diamond Card from the Riverwalk Casino in Vicksburg, MS. According to their website, other levels include base blue Player Rewards, orange Double Diamond card and a black Triple Diamond card. There's also a red HONOR card for active and retired military.

Here's a link to the casino website with info on the new cards
http://www.riverwalkvicksburg.com/players

And here's a scan of the new Diamond card