Visby lenses (ground rock crystal)
Lentes de Visby (cristal de roca tallado)
- Date
- siglos XI-XII · confidence medium
- Place
- Visby, Gotland, Sweden
- Credited to
- Viking-age craftsmen of Gotland
- Field
- Communication
⚠️ Disputed: the sources disagree.
What it is
About ten rock-crystal lenses, some aspheric and of notable optical quality, found in graves and churches of Gotland. It has been suggested that they served as magnifiers or reading lenses long before spectacles.
It is debated whether they were magnifying instruments (Tilgner, Schmidt and others) or merely jewellery and shrine ornaments; no texts document their use.
What it led to
- hypotheses about magnifying lenses in medieval northern Europe
- interest in aspheric rock-crystal grinding