The jet setting Italian, born in Manhattan, passed on at the age of 74, according to public Facebook posts from his friends.
"I'm so grateful to meet you. Thank you for living here with us. Don't worry. We won't forget you. See you later, dear friend. Goodbye, goodnight," Mazzuchelli's Croatian pal Lenka Gospodnetic has written on her Facebook profile.
In the 1990s, Ivana had split from Donald Trump in the wake of his affair with Marla Maples; and Mazzucchelli wooed her quickly. He reportedly showered the socialite ex-billionaire's wife with jewelry, as PEOPLE reported.
Businessman Mazzuchelli lived large, driving a Rolls-Royce and owning a pricey townhouse in London as well as keeping lavish New York digs.
Ivana also was known for her lavish lifestyle.
Ivana fell for the suave Italian's charms and they wed in 1995 but split just 20 months later and divorced in 1997. He was her third husband.
Ivana, the mother of Donald's three older children, filed a $15 million breach of contract suit against Mazzucchelli for allegedly violating the confidentiality clause in their prenuptial agreement. The suit was settled out of court.
Mazzucchelli once said, "I loved Ivana a lot, and I think I did my very best."
Ivana had told PEOPLE during the bitter divorce, "Riccardo's claim that he dumped me is totally untrue!" She insisted it was she who had left the charmer.
Ivana, now 68, would go on to marry a fourth husband, Italian toyboy, Rossano Rubicondi. She was 59 and he was 36 at the time. But it didn't last and they divorced in 2009.
As RadarOnline.com has reported, Ivana has been known for her cougar ways in recent years.
She also has continued her big money living as a single woman.
For almost ten years, Mazzucchelli had lived inside the walls of 1,700 year old palace of Roman emperor Diocletian in Adriatic port of Split, Croatia. The entrepreneur was part of a team who ran Floriana restaurant in London.
Some other Croatian friends of Riccardo Mazzucchelli wrote R.I.P. under his pal's Facebook tribute this weekend.
According to friends, Mazzucchelli will be buried in Jablanac, northern Adriatic, Croatia, where he recently built a grave.
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