Michael Irvin says someone stole one of his favorite pieces of jewelry -- a diamond necklace with TONS of sentimental value -- and he's mortified that it's now gone.
The Dallas Cowboys legend lamented losing the piece to his social media followers on Wednesday ... saying the ice was jacked by a thief in Miami last weekend.
Irvin says when he was returning to his hotel from a Univ. of Miami football event ... he set his black Louie Vuitton bag down -- which had his necklace in it -- to interact with some fans.