Ruling on selling gold for gold with an increase

Your Eminence! This message reached us from its sender, Muhammad Abdullah al-Haddadi, in Jeddah. He says: “May you be granted virtue! A doubt regarding riba, or perhaps it is riba itself as I believe, though I am not sure, has appeared among the gold sellers. That is: if a person comes carrying various types of gold jewelry and intends to exchange them for jewelry of the same type, the gold owner—that is, the seller—may weigh this gold to buy it with an equal amount of gold of the same type of jewelry, but he demands a large increase on the gold. Is this riba? Please rule for us, may Allah reward you, and may Allah guide you.”
Answer: In the name of Allah, the Most Gracious, the Most Merciful. Praise be to Allah, and may Allah send prayers and blessings upon the Messenger of Allah, and upon his family and his Companions, and upon those who follow his guidance.
As for what follows: It is established from the noble Prophet (peace and blessings be upon him) that he said regarding gold: So if this goldsmith or … gold seller demands an increase on the weight, he falls into riba. If the weighed jewelry weighs twenty mithqals and his gold is the same, but he wants the one giving it to add paper money, from paper currency, then this is not permissible; because it corresponds to a part of what is given … from him, so he would be selling the gold for less than its value, and the Messenger (peace and blessings be upon him) said: So the conclusion is that if one sells gold for gold, they must be equal, with no increase of one over the other, neither of the same kind nor of a different kind. If one of them adds paper money or any other goods, riba occurs; because the Messenger (peace and blessings be upon him) said: And by this you know that this sale is riba. Yes.