Selling silver and gold; selling banknotes with disparity

Question

Question: Is it permissible to sell a paper rupee for a paper rupee, or for a rupee of base-metal alloy, with disparity (with less or more), or not?

Answer

If silver is sold for silver, equality and mutual taking of possession (taqabud) are conditions; the same holds for gold. Silver in which silver predominates has the ruling of silver, and gold in which gold predominates has the ruling of gold. When the kinds (jins) differ, equality is not a condition. If the silver is in the minority and the alloy (ghishsh)

Source: Fatawa Mahmudiyya

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