NFL's Cordarrelle Patterson: My School Spirit Cost $15k!!!

Minnesota Vikings speedster Cordarrelle Patterson is showing love like all rich men do ... with diamonds ... blingin' out a custom neck piece to honor the two schools he loves.

TMZ Sports spoke to Albert Bekdas -- owner of Labelle Jewelry in New Jersey -- who tells us CP tasked him with combining his high school and college logos into one kick-ass piece.

That apparently entailed combining 10 carats of diamonds with 5 carats of sapphires into a shiny behemoth that set Patterson back over $15K.

And you thought showing up to the reunion was enough ... slacker.