"It's a black diamond, perfect for us," Electra tells PEOPLE. "Different – it's our style."
Celebrating in Austin with her fiancé, guitarist Rob Patterson, 37, while hosting the Dos Equis party to find a new assistant for the Most Interesting Man in the World, Electra was beaming.
"We are so happy," the model-actress told PEOPLE. "This is a really happy time for both of us."
The couple have been dating less than a year. It will be Electra's third marriage.
"This relationship is different than the others," she says. ""It's so special. We both feel it's an important thing right now, and we want to keep everything special, so we're keeping everything secret for now."
Patterson popped the question over the weekend. "It was my birthday, and we were celebrating in Las Vegas together, so [The engagement] was my birthday present," she said.
"It was just the two of us and it was really romantic, he asked me while we were alone in our hotel room." Did he get down on one knee? "I'm not saying, but it was really romantic," she said.
Some Things SecretChimed in the groom-to-be: "We do want to keep some things secret. It's funny, though. A lot of people don't know that we actually met like eight years ago, and then reconnected. Most people think we just met."
Elucidating further, Electra added, "We actually went out on a date like, eight years ago, while he was on tour. And then we sort of just went our own way with everything, then we reconnected about six months ago. We started off as friends and then everything has just gone on from there. It's really beautiful."
Regarding a potential wedding date, she said, "We don't have a date set or anything planned yet. We just want to take our time and really enjoy being together. We could be engaged for a while. … We want to take things slow. It's a really serious commitment for us, and it's beautiful."