Actress Grace Gummer has sparked speculation that she is set to marry Mark Ronson after showing off a large diamond on her left ring finger.

The Uptown Funk! hitmaker was first spotted on a dinner date with Mr. Robot star Grace in New York last September, and on Saturday, the happy couple was photographed hugging and kissing while out for a walk in London.

However, it wasn't just the public display of affection which has drawn attention - the images show Grace rocking a lone sparkler on her left hand.

According to the New York Post's Page Six, the loved-up pair spent part of Saturday having lunch with Mark's mother, Ann Dexter-Jones.

Representatives for the stars have yet to comment on the news, which emerges nine months after Grace, the daughter of Meryl Streep and Don Gummer, finalised her divorce from musician Tay Strathairn.

Meanwhile, Ronson's 2011 marriage to French actress and singer Josephine de La Baume officially ended in 2018.