The jewels, estimated to be worth up to USD 332,000, lay hidden in a metal box that was on board an Indian plane that crashed in the desolate landscape some 50 years ago.
The climber turned the haul in to local police.
"This was an honest young man who very quickly realised that they belonged to someone who died on the glacier," local gendarmerie chief Sylvain Merly told AFP.
French authorities are contacting their Indian counterparts to trace the owner or heirs of the jewels.
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Under French law, the jewellery could be handed over to the mountaineer if these are not identified, Merly said.
Two Air India planes crashed into Mont Blanc in 1950 and in 1966. Climbers routinely find debris, baggage and human remains.
In September last year, India took possession of a bag of diplomatic mail from the Kangchenjunga, a Boeing 707 flying from Mumbai which crashed on the southwest face of Mont Blanc on January 24, 1966.