Your jeweller friend is correct about hallmarks. However, many people incorrectly call every mark on metal a hallmark. The key point about a hallmark is that it is applied by an independent body which has tested that the precious metal content is as claimed. It therefore follows that electroplate, which has no silver content apart from a microscopically thin surface layer, cannot be hallmarked; any such marks on electroplate are applied by the manufacturers themselves.
A very good site for electroplate marks is https://www.silvercollection.it. You may have to drill down into the site to isolate electroplate marks from any particular country and you should bear in mind that electroplate marks are not as well documented as silver marks.
Phil