The huge ring that Mariah Carey has been sporting has intensified rumors that she and Nick Cannon are not only dating, but are now engaged.      

The New York Post's Page Six quotes a source who claims Cannon bought the rock for her and proposed marriage. The actor reportedly purchased it for $2.5 million at Jacob & Co. on East 57th St. in New York.      

"Maybe he's making payments on it," laughed the Page Six source, who claims to have overheard Cannon telling Jacob Arabo that he and Carey will be married.       

The ring is said to be 17 carats, with a 10-carat center stone, and made of rare pink and purple diamonds.