What is the ruling when the physical item (*ayn*) of a usurped property diminishes in substance but not in monetary value?

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The ruling when the substance of a usurped item diminishes, but not its value, is divided into three categories. First, if the diminished part has a determined equivalent (*badal muqaddar*), such as the physical deterioration of a gelded slave, reduced oil from boiling, or a dent struck into metal money, the guarantor must compensate for the diminished substance using its determined equivalent, while returning the remainder. This applies because the diminished part has a fixed measure, requiring its measure to be compensated, similar to total destruction. Second, if the diminution is not quantified, such as a very fat slave losing weight without a decrease in value, only the return of the slave is required. This is because the Law only mandates compensation for a decrease in value or a quantified equivalent, and neither occurred. Third, if the diminution is in a quantified equivalent, but the loss involves unintended components, such as the water content evaporating from grape juice (*'asir*) during boiling, leading to a decrease in substance without a decrease in value, there are two views. The primary view is that only the return is obligatory because the heat intended to remove the water, which often increases sweetness and value, meaning no compensation is due, similar to the fat loss in a slave that does not reduce value.