Original Artworks (excluding Artist Mugs) come with a Certificate of Authenticity, confirming provenance* of the artwork
Most ceramic works feature an artist stamp on the base, also supporting provenance
Works on paper are signed, dated and numbered according to series or edition
*Provenance speaks to the ownership / stewardship of an artwork over time. If you were to sell or gift an artwork, a Certificate of Authenticity evidences that the described work was truly made by the named artist.