By Emily Rome
June 04, 2013 at 12:00 PM EDT

British actor Jared Harris (Mad Men, Sherlock Holmes: A Game of Shadows) has popped the question to his longtime girlfriend, television and radio personality Allegra Riggio. The couple announced their engagement via Twitter and Vine, where Riggio showed off her new heart-shaped diamond ring.

We’re engaged! <3 #TeamHarris

— Allegra Riggio (@Allegratastic) June 4, 2013

People reports the custom-designed engagement ring features the letter “H” on the gallery and diamonds around the band.

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