NBA Lottery Pick Thomas Robinson -- I'm Gonna Spend My NBA Cash On ...

Thomas Robinson is projected to be a top 5 pick in the upcoming NBA Draft ... which means he's gonna be RICH ... and he's already got an investment strategy -- DIAMONDS.

The former Kansas Jayhawks superstar was outside of Katsuya with a group of buddies ... a group that included Syracuse superstar Scoop Jardine ... who's ALSO expected to be drafted.

The guys couldn't have been nicer ... but it's obvious, they have VERY different ideas when it comes to spending their money.

Robinson -- 6'10" and 240 lbs -- was also sporting a Washington Nationals hat ... interesting, considering some NBA insiders are projecting that he'll go to the Washington Wizards.