The biggest names in the NFL's rookie class -- from Joe Burrow to CeeDee Lamb -- are getting ready for their big day in the most baller way possible ... by going all-out on some JEWELRY!!!

TMZ Sports has learned ... LSU superstars Burrow, and Patrick Queen, Oklahoma's Lamb and Jerry Jeudy and South Carolina's Javon Kinlaw -- who are all potential first-round picks -- hit up Leo Frost in Houston to get their ice fix before taking the stage at the Draft on April 23.