Mariah Carey was spotted wearing a 17-carat diamond ring on her ring finger last week, and though she refuses to say whether it’s an engagement ring, a source confirmed to pagesix.com that it’s definitely from her boyfriend, actor Nick Cannon, and that two are now engaged. Cannon paid $2.5 million at Jacob & Co. last week for the ring, and the witness overheard Cannon telling Jacob Arabo that he and Mariah are set to marry. The ring has a 10-carat center stone, and is made of rare pink and purple diamonds. However, when Cannon, who’s been engaged before, dropped by MTV on Monday, was asked about the engagement rumors, he squirmed, saying, “I can’t even know what to say. She’s probably the most festive, remarkable person I’ve ever met. Good friend.” The two have been linked together for less than a month, when People.com ran a piece on their trip to Las Vegas.