The shape and style of an artefact changes through time although its function may remain the same.
There are relatively few dating laboratories and having an artefact dated can be an expensive exercise especially if the artefact is not of great value itself. I have a gold ring which I believe is ancient but also important! The way it's constructed, the way the internal sides of the rings gold are melted with faults that look like bits of silver And the slightly differing colours, the hand carved gem and its,inscription!
Archaeology dating techniques can assure buyers that their item is not a fake by providing scientific reassurance of the artefact's likely age.