Allegra Riggio and Jared Harris
Stefanie Keenan/Getty. Inset: Courtesy Erica Courtney
06/04/2013 at 05:00 PM EDT
Jared Harris should be feeling anything but Mad
The former Mad Men
star, 51, is engaged to his longtime girlfriend, Allegra Riggio, 38.
Riggio couldn't hold back her excitement on social media, posting a Vine
of her heart-shaped Erica Courtney sparkler and Tweeting
up a storm about the engagement, which was first confirmed by an E! News
"SOOOOOOOO HAAAAAAAPPYYYYYYYY AAAAAAAA!" the brunette beauty wrote
to one of her followers.
In response to another follower who congratulated the pair, Riggio wrote
, "THANK YOU!!!! We're giddy and adorable. <3"
As for the diamond itself, according to a release sent out by the jeweler, the heart-shaped diamond rose gold engagement ring was custom designed. It features an "H" initial on the gallery, and also has diamonds placed around the band.