The couple ended their relationship in October 2016, but Carey has been spotted wearing the ring since then, including in outings with her new partner Bryan Tanaka.
Last month Packer was photographed in Aspen with a new girlfriend, believed to be a New York socialite and model named Kylie Lim.
Social media photos of Lim show a surf-loving, bikini beauty who enjoys the outdoors.
It is understood Lim is aged in her 30s and has been dating Packer, 50, for several months following his split with Carey.
The pair were spotted holding hands and embracing in the luxury ski resort of Aspen.
Those pictures came after Packer opened up on his "Mariah Carey mistake".
The businessman, who turned 50 in October, told The Weekend Australian he was not in a good place when he started dating Carey.
He says when he met Carey in 2015 he was in billions of dollars in debt after borrowing big to provide sister Gretel with some of the money left in their father Kerry Packer's estate. He was also losing money on his Hollywood venture, RatPac, with friend Brett Ratner.
"I was at a low point in my personal life," Packer said.
"Documenting the negotiations with my sister was taking longer than expected. Brett Ratner put Mariah and me together. She was kind, exciting and fun. Mariah is a woman of substance. She is very bright. But it was a mistake for her and a mistake for me."
Packer declined to comment further, including about whether Carey got to keep the $12.7 million engagement ring and if she requested a $50 million settlement when they split.
Carey was reportedly heartbroken after Packer called things off.
When asked about Packer's whereabouts earlier this year, she said: "I don't know where the motherf**ker is."
Packer also revealed in the wideranging interview some strain in his relationship with Ratner and Crown Resorts' (of which he is a board member) trouble in China.
"My disappointment … is there were three sides to the business: the Warner Brothers slate that we broke even on, the stuff we did in China that we broke even on, and the films (Ratner) picked that we lost money on. His job was to pick films and to help us raise further capital," he said.
"If I was going to deal with getting out of Macau, the last thing I needed was to be in RatPac, which was losing money.
"People going around saying I was doing this to party … [it's] unfair and not what (Warner Bros CEO) Kevin Tsujihara or Steve Mnuchin would say. Brett is a force of nature. Our relationship is OK.
"Let's just say I did more for Brett than he did for me. But it was amicable with Brett in the end."
