Tyler Herro is just a rookie, but he's turning into a vet baller right before our eyes ... by copping some insane diamond-filled chain ... and it's worth a whoppin' $30k!!!
The 19-year-old ex-Kentucky star has been a stud in his first year in the Association ... he's currently averaging 13.4 points a game and has already gotten praise from ex-Miami champs like Chris Bosh.
TMZ Sports has learned ... Herro wanted to immortalize his own "TH14" logo in bling, so he hit up celeb jeweler Iceman Nick to make it happen.