The content originally appeared on: Urban Islandz Mariah Carey now has the biggest-selling holiday single. The record has the distinguished title of being the first holiday single to be certified Diamond, and it’s just another Diamond added to Mariah Carey’s stash. The beloved song, which rings in the Christmas season as a tradition for many the minute Thanksgiving ends, was certified diamond on Friday by the Recording Industry Association of America (RIAA), making it the first holiday song to achieve […]