Read more:
• From Shortland Street to Santa Monica
• Kiwi star's fiery Thrones role
The happy couple is reportedly considering exchanging vows in Tahiti and, according to the New York Post, the nuptials are also likely to involve James' super yacht.
Talking about her big day back in February, Mariah told Access Hollywood, "(It's going to be) very private (and there won't be) tons of people. I'm most excited about the grandeur, darling. It's not gonna be a big wedding. But it's going to be grand."
"I think the most important thing is the relationship and, you know, just the connection," she added. "That's the most important thing, but of course I love a grand moment."
Her engagement certainly was just that - Packer proposed during a private dinner with close friends and family in New York on 21 January.
"It's so heavy I can't lift my arm up!" she joked to E! News when asked about the huge diamond sparkler he gave her. The emerald-cut stone was designed by Wilfredo Rosado.
"It was very romantic," Mariah said of the proposal. "He's (Packer) an exceptional person and really... it gets more romantic by the day, so it's very sweet."
Her upcoming wedding to James will be Mariah's third - she wed Tommy Mottola in 1993, and Nick Cannon, the father of her twins, in 2008.
It's also the third time luck for Packer who was married to Jodhi Meares from 1999 to 2002 and Erica Packer from 2007 to 2013.
- WENN