Amazing gesture from Dak Prescott ... the Dallas Cowboys QB gifted his older bro with an incredible diamond moose pendant to remember their late brother -- and TMZ Sports has learned it was all super emotional.
We're told in mid-November, Dak hit up Paul Mazza at Mazza New York to try to get a birthday gift made for Tad Prescott -- Dak's older bro -- in time for his Nov. 25 celebration.
Mazza tells us he and Dak got to talking about possible jewelry pieces for the occasion .