Mark Von Holden/WireImage
07/31/2007 AT 10:00 AM EDT
Ivana Trump has decided to marry again, according to her rep.
Trump's on-again, off-again boyfriend Rossano Rubicondi, 35, recently presented the 58-year-old socialite, who famously divorced Donald Trump
in 1992, with a boulder-sized pink diamond, reports the New York Post
's Page Six
"It's a definite engagement," Ivana's longtime publicist, Catherine Saxton tells PEOPLE. "She hasn't made a formal announcement because they're still away in the Mediterranean. She wants to make a more formal announcement in September, when she's back in New York with her family."
Ivana and Rubicondi met on the Riviera in 2002. "They were introduced by friends," says a source close to her. "They've been together for five years. They have a great time together. They're very happy."
This will be Trump's fourth marriage.
The Czech-born Ivana was first married to childhood sweetheart George Syrovatka, whom she wed in the late 1960s and reportedly divorced in 1976. The following year she married The Donald, whose nickname she had coined during their 13-year marriage.
Shortly after their divorce, she married Riccardo Mazzucchelli. That union lasted less than two years.
also reports that Trump is currently vacationing on a yacht in the South of France and that her three adult children by the real-estate mogul – Donald Jr., Ivanka and Eric Trump – had not been made aware of her new marital plans.
When asked by the paper about his mom's next wedding, Donald Jr., 29, reportedly replied, "You probably know as much as I do."
Reporting by KC BAKER