With rumors swirling that Mary-Kate Olsen got engaged to longtime boyfriend Olivier Sarkozy last month, we're now learning more about the gorgeous vintage ring she's been wearing on that finger. So how much did it cost?

According to StyleCaster, the ring (see photo below) is vintage Cartier and dates back to 1953. It was reportedly purchased at a Sotheby's jewelry auction in NYC on February 6. News broke of the couple's engagement a few weeks later, on February 28. The ring's diamond is European-cut and is approximately four carats. It is surrounded by 16 sapphires, and there are single-cut diamonds on the petals.

Credit: Sotheby's

So the big question now is: What's the damage? The ring sold at Sotheby's for $81,250, far surpassing the $40,000 to $60,000 that it was expected to bring in. And while that clearly isn't dirt cheap, it's still more reasonable than what some celebrities have shelled out for engagement rings. For example, Kanye West's ring for Kim Kardashian is estimated by some to be worth close to $8 million. Yowza. 

Regardless of the ring's cost, we wish Mary-Kate, 27, and Olivier, 44, all the best. We had our doubts about their relationship at first, given the dramatic age difference, but they seem truly happy together. Are we hoping they get married soon? To quote Mary-Kate's character's catchphrase from Full House, "You got it, dude!"

What do you think of Mary-Kate's ring? And do you think this couple is a good match?

Source: StyleCaster