Gittin 74 - Divorce on Condition of Payment
If a man told his wife, "This is your Get on condition that you give me 200 zuz (~$10,000)," then she is divorced, and the Get takes effect retroactively to the time of giving the Get, at the moment when she gives the money. Therefore, if the Get is meanwhile lost or destroyed, it still works.
If he said, "On condition that you give me the money within 30 days," - then if she gave him the money within 30 days, she is divorced, but if not, she is not divorced.
If he says "On condition that you give me a certain garment," and the garment is lost - she is not divorced. Rabban Shimon ben Gamliel says that she can pay money for the garment, as it once happened in the city of Tzidon, but this is one of the three cases where the law does not follow him.