However the actress has now praised her on-the-ball fiancé for choosing the 'elegant and cool' diamond which she said perfectly suits her understated look.
"It is so me" she gushed to InStyle magazine, "I especially love that the diamond is flat—you can see my skin through it, which makes it even more understated."
The round, faceted stone sits on a rose gold band, and Mandy admits; "you wouldn't even know it was an engagement ring if I didn't wear it on my left hand".
Taylor picked the ring at jewellers Irene Neuwirth, and Mandy now says it's a symbol of their life together.
"When my boyfriend and I started talking about getting engaged last year, I told him I didn’t want a big ring. I figured we could just pick out some pretty bands together. So you can imagine how surprised I was when he proposed with this beautiful ring in the fall," she told InStyle. "Even though I thought I didn't want an engagement ring, as soon as I saw this one, I couldn't imagine the moment without it."
About the proposal, Mandy says it was as understated as the ring, with Taylor popping the question in September 2017.
"It was very unexpected and very romantic," the actor and singer, 33, told US magazine show Extra.
Mandy has been busy attending a number of lavish awards ceremonies over recent weeks and in January celebrated the 16th anniversary of the tragic teen romance A Walk to Remember with co-star Shane West.
The adaptation of the Nicholas Sparks novel won Mandy and Shane legions of young fans when it was released in 2002.
This is Us star Mandy posted a snap of their characters Jamie Sullivan and Landon Carter on Instagram and captioned it: “Jamie + Landon, 16 years ago, A Walk to Remember,” along with a heart emoji.