David Knell (Ancient Heritage Friday, 17 July 2015) wrote some thoughts on 'Your typical "antiquity" on eBay - where did it come from?'.
As usual, apart from the dubious assurances of "Thames find" and "British found" by the seller, there is absolutely no indication of where the item came from. A provenance (collecting history) for an item is not only an ethical precaution against inadvertently acquiring looted artefacts; as Elizabeth Marlowe rightly pointed out, it is also an important factor in avoiding fakes. Dealers in fine art have accepted for decades that a work purporting to be by a top artist is worth very little unless accompanied by a watertight provenance. The antiquities market, both high-end and low-end, is every bit as notoriously saturated with fakes as the fine art market. Perhaps it is time that a similar standard for provenance is more widely adopted for antiquities.