Sienna Miller, 38, teases a glimpse of her dazzling diamond ring in NYC

Sienna Miller, 38, teases a glimpse of her dazzling diamond ring in NYC amid engagement rumours with beau Lucas Zwirner, 29

She is said to be engaged to toyboy boyfriend Lucas Zwirner, 29. 

And Sienna Miller teased a glimpse of her dazzling diamond ring during a low-key stroll in New York City on Tuesday.

The American Sniper star, 38, cut a casual figure in a pair of grey skinny jeans with a matching coloured jumper.

Bride-to-be? Sienna Miller teased a glimpse of her dazzling diamond ring during a low-key stroll in New York City on Tuesday

Adding some stylish touches, Sienna opted for a blue pinstriped longline coat with a pair of Gucci trainers and a white crossover handbag.

The star left her signature blonde locks loose into a relaxed hairdo, she appeared to go make-up free as she showed off her radiant complexion.    

Sienna was not joined by her partner Lucas, after friends confirmed to The Mail on Sunday this weekend that the actress said ‘yes’ when Lucas popped the question last month.   

Low-key: The American Sniper star, 38, cut a casual figure in a pair of grey skinny jeans with a matching coloured jumper

Low-key: The American Sniper star, 38, cut a casual figure in a pair of grey skinny jeans with a matching coloured jumper

The couple, who began dating last year, are said to be blissfully happy together and have begun making plans for their wedding.

She and Lucas, the editorial director of his father’s art-based publishing house, David Zwirner Books, are understood to have moved in together in New York.

Sienna was previously engaged to Tom Sturridge, who she split from in 2015 following a four year romance, and with whom she shares daughter Marlow, seven.  

Her most iconic relationship so far was with her Alfie co-star Jude Law. 

Details: Adding some stylish touches, Sienna opted for a blue pinstriped longline coat with a pair of Gucci trainers and a white crossover handbag

Details: Adding some stylish touches, Sienna opted for a blue pinstriped longline coat with a pair of Gucci trainers and a white crossover handbag

The former on-off couple got engaged on Christmas Day 2004, they ended in 2006 before reuniting in 2009 and splitting again in 2011.  

The actress recently admitted that she was open to the idea of walking down the aisle. 

She told The Sunday Times’ Style: ‘Yes, I would love to have more children. I would love a daughter as well. I think I would be open to getting married, yes.’

And speaking about her relationship with art gallery owner Lucas, she added: ‘It is interesting to be in a world that is not the one I am in.

‘I felt like I’d been in every room somehow and the art world is very new and fascinating, and very intellectual, which I love.’

Cute couple: Friends confirmed to The Mail on Sunday this weekend that the actress said 'yes' when Lucas popped the question last month (pictured at the Writers Guild Awards)

Cute couple: Friends confirmed to The Mail on Sunday this weekend that the actress said ‘yes’ when Lucas popped the question last month (pictured at the Writers Guild Awards)