Michel Elias Germani, 65, is doing "extremely poorly" behind bars after handing himself in earlier in May, John Korn said outside court on Wednesday.
He spoke to reporters after a magistrate refused to grant his client's release.
Germani is accused of being in on a robbery at his eponymous jewellery store in Sydney's CBD in January, telling police two men threatened him and his employee with a knife, tying them up and demanding access to a safe before taking off with more than $2.8 million in jewellery.
Investigators allege it was a scam orchestrated by the award-winning jeweller to defraud his insurer.
Court documents seen by AAP allege Germani sought $2,821,348 from Barrenjoey Insurance, underwritten by Lloyds of London, allegedly making false statements to do so.
He has been charged with second-degree aggravated robbery and depriving a person of their liberty, attempting to dishonestly obtain a financial advantage by deception, publishing false or misleading material to obtain property, participating in a criminal group and contributing to criminal activity.
Mr Korn sought Germani's release on Wednesday, telling the court any trial would not take place before 2025 and it would be "inimical" to the justice system to keep him in custody until then.
Seven people had provided sureties in the amounts they could spare for a total of $105,000.
Germani's wife is struggling to run the store and his son needs his help to meet the heightened needs of his own child, Mr Korn argued.
The matter is in its infancy, with no evidence yet served, but the case is suggested to be a strong one, Magistrate Daniel Covington said, refusing bail.
There were also "suggestions" from police of a "highly organised operation", he said, and an unacceptable risk Germani would attempt to flee, interfere with witnesses or evidence, or commit a serious offence while on bail.
Outside court, Mr Korn said it was a disappointing and poorly reasoned decision.
"This case in my opinion is just going to fall apart when the police start digging into it.
"They've got co-accused who've got massive incentives to tell a story that ingratiates them to the police, and I'm going to pull it apart," Mr Korn said.
Germani needs to be released so he can start preparing his defence and set about clearing his name.
"He's grossly insulted at the suggestions that are being made, but what can he do about it at the moment?" Mr Korn said.
Germani's case returns to court on July 6.
