Amber Heard's engagement ring is believed to be worth almost $100,000.

Johnny Depp's new fiancee was spotted showing off her large diamond accessory for the first time as she watched him perform at a private charity event in Anaheim, California on Sunday night.

"This looks like a 5-carat ring. If we assume it's a white oval diamond in the five carat range, the price would be between $78,000 to $100,000," celebrity jewelry expert Zaven Ghanimian told EOnline.com

The blonde beauty, who hid the ring from photographers last week, is likely to have helped Johnny choose the ring as a source previously revealed that Amber "calls the shots" in her relationship with her The Rum Diary co-star, whom she began dating in 2012. "Amber has called the shots since day one, dictating when they went public, for example. She's half his age and that's part of why he'll do whatever she wants in order to keep her," an insider said.

"He has definitely toned down his behaviour since he started dating Amber. He acts like a mature and charming man now," another insider said.

The 50-year-old actor - who has daughter Lily-Rose, 14, and son Jack, 11, with former partner Vanessa Paradis - is said to be attracted to the way Amber has her own way of doing things and doesn't "go with the flow."