Gabrielle Union showed off her engagement ring and shared the story behind the surprise proposal from fiancé Dwyane Wade.

During an appearance on "Good Morning America," Wednesday, the "Being Mary Jane" actress revealed how the Miami Heat guard's sons Zaire, 11, and Zion, 6, helped their dad pop the question.

The actress said Wade's proposal caught her off guard because she thought it was just a regular fun day with the kids. After having lunch, the gang went to visit their home that was currently under construction.

Union said during the tour Union said Wade's son called out to the couple, "We wanna do a presentation for you."

"Me and D turn around and they're like, 'OK, now!' And they're holding signs that say, '... Will you marry us?'" Union recalled. "But the thing is, they ask me all the time, so I was like, 'Oh, this is embarrassing! Now they've made signs!

"I turn to D like, 'Here we go!' and he's down on one knee."

The "Good Deeds" actress, who shared a picture of her ring on Instagram shortly after, said was "clueless" about the planned proposal, joking that her nails looked horrible and she regretted not using lotion for her hands.

"I should have known something was up when [Dwyane] was like, ''Are you gonna do your hair? Are you gonna put on makeup?' I'm like, 'To go to a construction site? No," Union said.

According to E! New, Jason Arasheben, CEO of Jason of Beverly Hills said the engagement ring features included a "cushion-cut diamond worth 8.5 carats" and is valued at nearly $1 million.

"Dwayne Wade was 100 percent involved in the process," Arasheben said. "I made three personal visits to Miami to present different options until they found the perfect one. Wade picked out the stone and they made the ring custom."