India, April 23 -- American actor Zoe Kravitz and English singer Harry Styles have set off fresh engagement chatter after being photographed in London. In images shared by The Sun, the two were seen sharing a kiss. But what caught eagle-eyed fans' attention is a striking diamond Zoe, 37, wore on her left hand's ring finger as she roamed around with Harry, 32, on April 19 and April 21. An onlooker told the publication, "Harry and Zoe look so in love - and she's got an enormous diamond on her ring finger. He is such a gent and led her to a waiting car before leaning in and giving her a kiss. When she left Harry waved her off. Zoe had a massive smile on her face. You couldn't miss the ring on her finger. It is absolutely huge." Their relationship first came into focus last August, when they were reportedly seen kissing at a restaurant in London's Soho. By December, sources indicated it was still going strong. They were said to have spent Christmas together at Harry's family home in Cheshire, before travelling to the Bahamas to ring in the New Year. htc...