Is Salam valid for commodities whose values vary significantly based on non-quantifiable characteristics?

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Salam is invalid for commodities whose value differs widely based on characteristics that cannot be strictly defined by measure or weight, such as gemstones like pearls, rubies, turquoise, chrysolite, and agate, because their prices vary immensely based on size, perfect roundness, brilliance, and clarity. These cannot be precisely quantified by reference to items like sparrow eggs or specific designated objects because those references are variable or perishable. This is the view of Shafi'i and the Companions of Opinion (Ahl ar-Ra'y). Malik's opinion allowed it if a known quantity of the specific item was stipulated by a known weight.