Yes. A bar without its assay card, blister or certificate can still be sold. The card is evidence. It is not the metal.
What the packaging usually tells us
A minted bar in intact branded packaging from a known refiner is quicker to identify. The stated weight and fineness on the card should match the bar. If the seal is split, the card is missing, or the bar has been taken out, we treat the identification as incomplete and test.
Cast bars are often sold without retail packaging. They are weighed and tested like any other gold whose stamp we need to confirm.
What changes when the card is gone
We cannot rely on a photograph of a certificate you no longer have. We can rely on the bar in the room: its weight, its marks and the assay we run in front of you. A bar that tests as fine gold is priced as fine gold. A bar that does not match its supposed fineness is priced on the reading, or declined if it is not what it appears.