Set to wed? Rumour has it that Marcus Mumford and Carey Mulligan are engaged. Photos:GettyImages/PA
If the Hollywood rumour mill is to be believed, diamond sparkler.
"Carey looked like the cat who had got the cream," one onlooker told the paper. "She was wearing a beautiful ring and didn't seem to mind who saw it."
"They were stuck to each other like glue."
The pair first met when Marcus' band Mumford and Sons performed in Nashville, Tennessee earlier this year - with the singer reportedly inviting 26-year-old Carey along to a private gig.
Marcus split from long-term girlfriend Laura Marling last year, while Carey had recently ended a high-profile relationship with her Wall Street co-star Shia LaBeouf.
We're keeping our eyes peeled for that ring!
Celebrity engagement rings
Other Half: Mike Tindall
State of Union: Engaged
Cut: Circle solitaire set in tens of pavé set diamonds
The ring is bespoke, and so far the carat count and value have been kept underwraps. Watch this space for an update!
Other Half: John Krasinski
State of Union: Married
Cut: Pear
Total Carats: 4
Estimated Cost: $75,000-$85,000
"Emily is a chic and simple girl and her pear shape diamond ring clearly signifies that in a very classic and romantic way."
Other Half: David Beckham
State of Union: Married
Jeweller: Boodle & Dunthorne
Cut: Marquis
Total Carats: 3
Estimated Cost: $65,000
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Other Half: David Beckham
State of Union: Married
Cut: Marquis
Total Carats: 10
Estimated Cost: $1 million
"The first ring is very simple. They got married when they were young, but if fits with where they were at the time. The latest ring is 8 or 9 carats large r- you can see the evolution of her into a fashion maven."
Other Half: Nick Lachey
State of Union: Divorced
Cut: Pear
Total Carats: 4
Estimated Cost: $75,000
"This is very, very classic. It's one of the first cuts and super romantic. You can tell Nick put a lot of thought into it."
Other Half: Jay-Z
State of Union: Married
Jeweller: Lorraine Schwartz
Cut: Emerald
Total Carats: 18
Estimated Cost: $5 million
"This is an investment piece. It's so rare, so large, and so clean. It's sort of like having money in the bank. It's better than having a 401K."
Other Half: Jared Kushner
State of Union: Married
Jeweller: Ivanka Trump Fine Jewellery
Cut: Cushion
Total Carats: 5
Estimated Cost: $150,000
"For a girl who really loves diamonds, this engagement ring is perfect, not too subtle, but not to flashy, just like Ivanka."
Other Half: Fred Armisen
State of Union: Divorced
Cut: Round
Total Carats: 4
Estimated Cost: $120,000
"This engagement ring is ideal for the "Mad Men" stunner - a modern, romantic diamond engagement ring that really highlights her chic, understated personality."
Other Half: Benjamin Gibbard
State of Union: Married
Cut: Asscher
Total Carats: 3
Estimated Cost: $40,000
"Zooey's ring is a classic diamond ring that fits perfectly with her clean, sleek indie style."
Other Half: Seal
State of Union: Married
Jeweller: Lorraine Schwartz
Cut: Cushion
Total Carats: 12
Estimated Cost: $1.5 million
"This cushion-cut canary diamond was designed by Seal who was obviously going for a fashion-forward statement, which is right for the model type like Heidi."
Other Half: Tom Cruise
State of Union: Married
Cut: Oval
Total Carats: 6
Estimated Cost: $100,000
"This is very romantic and a throwback to the early-to-late 20th century. It's unique because it has a pink pave shank around the centre stone."