A program of analytical characterization of 89 European Iron Age glass objects from a deposit in the Mathay-Mandeure celtic sanctuary has led to the exceptional discovery of seven previously unnoticed La Tène engraved glass beads. The working of cold glass is extremely rare in the Late Iron Age: heretofore, a single Celtic engraved glass bead was known from the Münsingen-rain cemetery. Examination of the objects and the study of their elementary composition bring new elements to our understanding of the depositional practices carried out at the sanctuary. The discovery also urges us to pay more attention to the potential of glass beads as a medium for bearing inscriptions.