According to reports, Valderrama, 33, purchased a stunning ring from Tiffany's in Pasadena, California and acted "really excited and happy", one of their employees told Hollywood Life.
"Yes, Wilmer did buy a ring here. We all talked about it afterwards because he was so darn nice," an employee said.
While she couldn't confirm that it was an engagement ring,
the Tiffany employee did say it was extremely stunning.
"He chose a really classic, beautiful ring. Demi is going to be a happy girl when she gets it. He didn't say what it was for but he was really excited and happy - he seemed like any other guy getting ready to pop the question.