It's Christmas in October for Mario Edwards ... the Tennessee Titans defensive lineman just spoiled himself by copping a massive 25-carat diamond pendant of his head!!
TMZ Sports has learned the defensive end wanted some new mini-me bling, so he hit up Ari The Jeweler to design the piece.

You see the pendant looks just like the 28-year-old ... from his hairstyle all the way down to his facial features and beard.
The pendant also has his jersey number, 97, inscribed on his forehead in diamonds.