A Certificate of Authenticity is provided with each archaeological piece as well as with any other quality object.

A thermoluminescence test is conducted on exceptional pieces (when this technique is applicable).

Whereas Carbon-14 dating is used to determine the age of biological material, thermoluminescence dating is well-adapted to terra cottas, ceramics, pottery and burnt stones.
Only performed in a few certified laboratories in Europe, the thermoluminescence test consists in drilling out small samples from an antique piece.
Then measurement of the luminescence intensity is used to determine the time elapsed since the last time the object was heated (e.g. last firing).

Each certificate of authenticity includes one or more pictures of the piece, its dimensions, its period, its origin, as well as a detailed description of it: material used to built the piece (bronze, terra cotta, etc), civilization to which the piece belongs, its region/country of origin, etc.
The certificate also includes a specific filing number that could be used to recover information if required (e.g. name of the expert who analyzed the piece, thermoluminescence test number, etc). The certificate is dated and signed on the day of purchase.