In the UK articles made of mixed metals can only bear a hallmark for the "lesser" metal. IE. something made from silver and gold can only be marked as silver.
The statement below is from the new guidelines on the UK Assay
Office’s webpages - They will also accept mixed precious metals and
stamp each separately and not just to the lowest one in the piece.
“As you may well be aware the UK Assay Offices are now able to
hallmarkarticles consisting of precious metal and base metal”. The
latest hallnote includes instructions for this to be carried out.
See the UK Assay Office websites for the full details.It probably
applies to other EU assay organisations as well as theyseem to be
more or less synchronised now.
Regards to all
Robin Key
Clavis Jewellery
Aberdeen, Scotland