Matthew Stafford just put the ICE in ice cream -- at least judging by the MASSIVE DIAMOND ENGAGEMENT RING his girlfriend was flashing at Cold Stone Creamery.
The Detroit Lions quarterback finally popped the question to longtime GF (and college sweetheart) Kelly Hall -- a former cheerleader at the Univ. of Georgia.
Hall posted a shot of the goods on her Instagram page -- subtly flashing the rock while munching down on some dessert.
She added the caption, "Don’t think I could be any happier!! #icecream."
As for the ring, no word on the size yet ... other than the fact that it's HUGE (good thing Stafford signed that $53 MILLION contract extension last year).