Ruling on lending and borrowing gold and silver

The matter is not as you mentioned in your question, because
lending and borrowing gold and silver is something that is permissible, and
there is nothing wrong with it. None of the Muslim scholars have disallowed
it, whether the gold and silver is in the form of coins, jewellery, ingots
or otherwise. 

So it is permissible for a person to borrow gold, so long as
he returns an equivalent amount at a later time. 

Ibn al-Mundhir (may Allah have mercy on him) said:

The scholars from whom we acquired knowledge are unanimously
agreed that it is permissible to borrow dinars (gold coins), dirhams (silver
coins), wheat, barley, raisins, dates and any other kind of foodstuff,
whether it is measured by volume or by weight.

End quote from al-Ishraaf ‘ala Madhaahib al-‘Ulama’
(6/142) 

It says in Murshid al-Hayraan (no. 69 0):

It is permissible to borrow minted gold and silver [i.e.,
that which has been made into dinars and dirhams] by weight, and also by
number, if the weight is accurate, and the borrower may return what he
borrowed in the form of a similar number of the same kind and weight, or he
may pay back the same weight but a different number. End quote. 

This has been explained previously in the answer to question
no. 136433. 

What is not allowed according to Islamic teaching is selling
gold and silver, one for the other (without the exchange taking place in the
same sitting as that in which the transaction is agreed upon) [riba an-nasee’ah],
or selling for a different weight if the transaction is gold for gold, or
silver for silver [riba al-fadl]. 

With regard to loans, the ruling is completely different from
the ruling on selling. The difference between the two has been explained in
the answer to question no. 131000.

Based on that:

The term riba an-nasee’ah is applicable with regard to
selling one currency for another, as it is applicable to selling gold and
silver.

And the term riba al-fadl is applicable to transactions
involving selling currency of the same type, just as it is applicable in the
case of selling gold for gold, or silver for silver.

The Islamic Fiqh Council has issued a statement concerning
banknotes, in which it says: Banknotes are something to which people have
agreed to give value, so they have value and they come under the established
Islamic rulings on gold and silver with regard to the rulings on riba,
zakaah, exchange of one type for another in the same sitting, and all other
rulings.

End quote from Qaraaraat wa Tawsiyaat Majma‘ al-Fiqh al-Islami
(p. 14).

In a statement issued by the Fiqh Council of the Muslim World
League, it says:

Paper currency is a separate type of currency that comes
under the same ruling as the two currencies of gold and silver. So zakaah
must be paid on it, and the rulings on both types of riba, fadl and nasee’ah,
are applicable to it, just as they are applicable to the two types of
currency, gold and silver – because paper currency has value – by analogy
with gold and silver. Therefore paper currency comes under the same rulings
as other currencies with regard to all the conditions and guidelines
stipulated by sharee‘ah.

Qaraaraat al-Majma‘ al-Fiqhi al-Islami li’r-Raabitah,
Makkah (p. 22)

For more information, please see the answer to question no.
129043

And Allah knows best.