Iranian Kurdish Caucher Birkar, 40, received the gold Fields Medal, which is considered math's equivalent of the Nobel Prize, on Wednesday.
Less than an hour later, it emerged that his briefcase containing the award had vanished and when the case was found later at the Rio convention center hosting the event, the medal was missing.
"On Saturday, he will receive an identical medal to the one that was stolen," said a spokesman for the International Congress of Mathematics, which organized the award ceremony.
Three other mathematicians were awarded the same prize, which is handed out only every four years.
The spokesman said that a fifth medal had been kept as a spare. All that remained to do was to have Birkar's name engraved.
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