The Hallmark Act 1973

If you are thinking of buying or selling something made of a precious metal on Folksy, it is important that you comply with The Hallmarking Act 1973, which requires all precious metals sold in the UK to be hallmarked (with some exceptions). This process independently validates the precious metal content of the item. 

Failure to comply with the Hallmarking Act is a criminal offence.

Items to be exported may be exempt from hallmarking depending on which country they are going to.

Further information:

A comprehensive guide to Hallmarking, including downloadable guidance notes, from the British Hallmarking council:
https://www.gov.uk/government/organisations/british-hallmarking-council

A summary of current Hallmarking legislation from Birmingham Assay Office:
http://assayofficebirmingham.com/legislation/current-legislation

The four UK Assay Offices:
London Assay Office
Sheffield Assay Office
Birmingham Assay Office
Edinburgh Assay Office