This object is eligible for a Certificate of BADA Provenance

A theatrical prop helmet, of sallet form, with an integrated crown decorated with acanthus leaf finials and semi-precious stones and glass, a soft arming cap to the inside with a label reading 'No: 7 Richard III Bristol', on a turned wooden stand.

English, 19th century

This was presumably made as a prop for a production of Shakespeare's Richard III at the Theatre Royal in Bristol, the oldest continually-operating theatre in the English-speaking world.