What is the ruling on recovering a portion of the manufacturing cost and the full assaying and stamping fees when selling a gold bar back to the same company from which it was purchased?

1. If gold is sold for currency or silver: There is no harm in any price agreed upon by both parties, provided that the exchange takes place in the same sitting, as the Prophet, peace and blessings be upon him, said: "Gold for gold, silver for silver... but if these categories differ, then sell as you wish, provided it is hand to hand." Currency is considered an independent category; therefore, equality is not a condition.

2. If gold is sold for gold: Equality and equivalence in weight are required, and any disparity is forbidden, whether the gold is manufactured or not, and whether it is good or bad, raw (unminted) or coined. If 10 grams are sold for 10 grams, then equality in weight is obligatory, and it is not permissible to pay an additional amount in cash or gold for the craftsmanship. The lawful method is to sell the old gold for currency, then buy the new gold with that currency.

It is forbidden to exchange gold for gold with the addition of a manufacturing fee, as this constitutes usury. One can sell used gold for a price, then buy new gold with that price. It is permissible for a jeweler to take gold from a customer for manufacturing purposes only and to take a fee for his work.