The 18-year-old goalkeeper, who has been recognised as the finest young talent in world football by winning Goal’s NxGn award, continues to generate plenty of speculation regarding his future.
He is a product of Milan’s academy system and owes the Serie A side plenty for having shown so much faith in him at such a young age.
The Rossoneri are, however, aware that they will need to match the ambition of a prodigious talent if they are to keep him at the San Siro.
They are already having to fend off talk of big-money bids from elsewhere, with recent speculation suggesting that City are prepared to pay £130 million to secure his signature.
Berlusconi is aware of the rumours, but he remains confident that Donnarumma can be kept out of the clutches of a European rival.
He told La Verita: “Gigio is one of Milan's jewels.
“He's a gorgeous product of our youth system, he feels strong attachment in his heart to the jersey and the Rossoneri colours. For us he's completely off the market.”
Pushing through the sale of Milan to Chinese investors could help to keep Donnarumma in his current home, but complications have been encountered in what has been a drawn out process.
Berlusconi added: “I'm committed, so is my family, we'll proceed with the sale of the club only if there are all the guarantees both financial and for the relaunch of the club.
“The Chinese buyers have been impacted by some difficulties that couldn't have been predicted, but they guaranteed significant down payments: we're ready to continue to maintain our commitments and think the buyers will with theirs.
“Should the deal not go through we'll continue to build a young and Italian team"