Does riba (usury or interest) apply to gold mixed with other substances if the other substance is not distinct?

Question : The calculation in the self-balance allows determining the difference in the link from the standard.

Answer : This does not cause harm. He says this is like salt in food; it has no effect. The apparent Sunnah and the apparent statements of the scholars indicate that there is no difference. However, if it is distinct, such that something distinct has been mixed into it, for example a strip of copper or a strip of lead, then this is a reality. The criterion is: whatever is named gold is gold. Yes. We say that if it is mixed with something that has substance, it prevents it from being sold for gold. But if it has no substance, just a color, there is no harm, because this is merely inherent adornment.