Rob Kardashian Paid $325,000 For Blac Chyna’s 7-Carat Engagement Ring

And he didn’t put just any ring on it—he put a seven-carat, round-cut brilliant triple excellence diamond on Blac Chyna‘s finger. The former E! reality star turned to his longtime friend, Ben Baller, founder of IF & Co., to design his fiancée’s custom bling. “She was really going crazy over the ring. She loves it. $325,000 is pretty close to what he paid, but it could have been a lot more because of the clarity. It’s hard to manipulate that kind of radiance on a diamond,” Ben told E! News Wednesday. Rob “paid for it himself” after reaching out to Ben about a week ago. “He called me and he was like, ‘I have some ideas,’ and he shot me over a few pics he saw on my IF & Co. Instagram page. He said, ‘What can you do for me?’ I said, ‘Trust me.’ And he agreed.”

After the call, they decided to meet up and discuss the ring in person. Rob and Ben spent two hours weighing their options. “He was smiling the whole time,” Ben said, adding that it took him five days to complete the design. Rob wanted to propose while Blac’s mom was still in town, so time was of the essence. “I was rushing to his house at like 9 p.m. that night,” he said.

Ben declined to share details of the proposal, however.

Rob popped the question Monday, sometime before Blac’s appearance at Ace of Diamonds in L.A. Though the couple didn’t take their relationship public until January, Ben believes they will go the distance. “What they have is genuine,” he told E! News. “It happened fast, but it’s real.” And, when the time comes exchange vows, “I’m sure I’ll do their wedding bands. I’m positive.”

Ben is also positive that Blac has helped Rob come out of his shell again. Consider the fact that Rob has been seen in public more in the last three months than he has in the last three years. “I know Rob pretty well,” he told E! News. “When he was going through his ups and downs, he avoided his best friends; he cut people off. Now, he’s genuinely happy again. The old Rob is back. He’s a prankster and he’s happy and he’s funny. He’s back to the old Rob and I’m glad to see it. I don’t know her that well yet, but if she got my boy back…She’s very sweet. She’s very cool.”