expects to be in Dallas for a LONG time ... at least, that's what it looks like after the dude invested in a sick, diamond Cowboys jersey with his name and number on it!!
Amari's team just got knocked out of the playoffs by the Rams, but now the dude can still rep his team in the off-season ... courtesy of the solid piece made of 40 carats of diamonds!!
TMZ Sports has learned ... A.C. hit up Gabriel the Jeweler -- the go-to guy for huge stars like Antonio Brown, OBJ and Jarvis Landry -- earlier this month to solidify his spot with America's team.