What is the ruling on interpreting 'counterfeit' (*zuyuf*) Dirhams?

Primary text

If the debtor specifies 'counterfeit' (*zuyuf*) and explains it means adulterated or having a flaw that reduces their value, the explanation is accepted. However, if the explanation specifies them as being made of copper or lead, or things having no intrinsic value as currency, the explanation is not accepted. This is because such materials are not truly Dirhams, and explaining them as such constitutes a complete retraction of the original admission, which is impermissible, akin to completely excluding an item from the admission.