He—may Allah have mercy on him—was asked:

Concerning gold combined with silver: if the quantities of silver and gold it contains are known, may it be sold for either metal, provided that the quantity of the metal given alone exceeds the quantity of that same metal in the composite?

He replied:

Praise be to Allah. This falls into three categories:

The first is when the intention is to exchange silver for silver in unequal amounts, or gold for gold in unequal amounts, adding something of a different kind to the smaller amount as a legal stratagem. This is not permissible at all.

The second is when the intention is to sell either metal and to sell merchandise for either metal, while the merchandise contains something not sought in its own right. Examples include selling weapons for either metal when they bear a small amount of ornamentation, or selling a property for either metal when its ceiling and walls bear similar ornamentation. This is like selling sheep bearing wool for wool, or sheep producing milk for milk. Most scholars permit this, and this is the correct view.

Selling silver coated with gold that disappears when melted down for an equal amount of silver also falls into this category. Thus, if worked, gilded silver is sold for gold, or if it is sold