Darren Gerrish / Getty Images North America 1 / 10
Darren Gerrish / Getty Images North America 1 / 10

Letting the rock do the talking! Dianna Agron is finally showing off her engagement ring.

Mumford & Sons' Winston Marshall proposed to the former "Glee" star over the 2015 holiday season, but she's kept the engagement ring under wraps until now.

How could she even manage to hide that thing for so long!

Dianna flashed her giant diamond ring on Feb. 22 while attending Erdem's runway show during London Fashion Week, but didn't speak about it.

The actress, per usual, looked gorgeous, rocking a blue and white floral dress, allegedly designed by Erdem's. She stunned as she used minimal makeup with her hair pulled into a low ponytail.

Still, though, it was hard to notice her outfit with the huge bauble, set in a gold band, on her finger.

Reports of the engagement were confirmed in January.

Both Dianna, 29, and Winston, 27, have been relatively quiet about their relationship ever since photos surfaced last summer showing them holding hands on a romantic stroll through Paris, where Winston's band was playing a show.

If they haven't been spotted out and about together lately, however, it's likely due to their busy schedules.

Recently Dianna began filming the nun drama "Novitiate," while Winston -- who was previously linked to Katy Perry -- began a tour with his music group at the end of January.

In August, the pair gushed over each other at the "She's Funny That Way" premiere afterparty at Sunset Tower in West Hollywood. "Dianna was smiling and laughing a lot, and seemed really happy," a source told Us Weekly at the time.

Dianna's sparkler is believed to be a 4- to 6-carat diamond set in yellow gold with a thick, simple band.

It hasn't been all happy news for Dianna's former "Glee" costar, though. It was reported this week that Lea Michele, who played Rachel Berry on the Fox show, and her boyfriend of two years, Matthew Paetz, have split.

"Their split is a huge shock to all their friends," a source told Entertainment Tonight. "Lea and Matthew were talking about getting engaged as recently as around the holidays. Everyone thought they would get engaged soon, but definitely not split."

While it's not known when Lea and Matthew actually split, they were last spotted together was on Feb. 8.