The investment bank Rothschild is said to have a mandate to find a minority shareholder in the Florence-based fashion house to further boost its business.
Clessidra and the Buccellati family will retain a 15 percent stake in the company.
The publicly listed Italmobiliare has secured the Italian private equity fund for roughly 20 million euros, or $22.7 million, at current exchange rate.
The private equity acquired a 67 percent stake in the jewelry brand in 2013.
The Italian private equity firm is in exclusive and binding negotiations with Italmobiliare SpA, an investment holding owned by the Pesenti family.