Eight people have been convicted in connection with a 2008 raid at a Harry Winston jewellery shop in Paris, in which three cross-dressing gunmen stole about $92 million in loot, a defence lawyer has said.

Lawyer Philippe Stepniewski said sentences ranged from nine months to 15 years in prison - with the heaviest penalty handed to Douadi Yahiaoui, a 50-year-old repeat offender and alleged ringleader of the heist.

In the robbery, the gunmen wore silky wigs, skirts, stockings and high heels, and took less than 20 minutes to steal hundreds of jewellery pieces and watches.

The eight were convicted late on Friday on charges including armed robbery in an organised gang, criminal association, and receiving stolen goods in the 2008 heist, and another a year earlier at the same store.

In that one, thieves dressed as building painters slipped in through the store's service entrance. All told, authorities estimated the two heists netted more than €100 million in luxury watches, necklaces, earrings and other valuables.

Mr Stepniewski's client, Mouloud Djennad, was a security guard at the Harry Winston store and an inside accomplice who tipped off the thieves to the amount of the bounty inside, according to court documents.

Djennad received a two-year prison sentence, and was one of two defendants in the case to be released for time served, the lawyer said.

Many of the jewels have not been found. Some turned up after police detained 25 people in a 2009 sweep.

Two years later, 19 rings and three sets of earrings worth some €18 million were dug out from a Paris-area rain sewer near Yahiaoui's house - hidden in a plastic container set in a cement mould.

Over the years, France has faced a number of brazen jewellery robberies, including three in the southern resort town of Cannes in 2013.

In one of those, a lone gunman sneaked into a posh hotel, held up a diamond show, and made off with a breathtaking $136 million worth of valuables in about one minute.