International conventions

Switzerland is member of the "Convention on the control and marking of articles of precious metals (Vienna Convention)".
Furthermore, Switzerland has concluded bilateral conventions with France, Italy, Austria, Spain and the Russian Federation; they have facilitated the trade for several decades now.

Convention on the control and marking of articles of precious metals

The Convention on the control and marking of articles of precious metals is an international treaty between states on the cross border trade in precious metal articles. It was signed in Vienna in November 1972. The objective is to facilitate international trade in articles of precious metals while at the same time maintaining consumer protection justified by the particular nature of these articles.

Articles bearing the common control mark - together with the national assay office mark, the responsibility mark and the fineness mark indicating its purity - do not have to be re-hallmarked in the contracting states. The national hallmark guarantees that the purity of the metal is at least that indicated by the fineness mark.

The multilateral convention's member states can be found at http://www.hallmarkingconvention.org/members.php.

Common Control Marks of the Convention

A precious metal article with a Common Control Mark stamped in Switzerland bears the following marks:

Bilateral Conventions

Bilateral Convention Switzerland-France
Mutual recognition of official hallmarks by both countries, eliminate a double control of articles in gold, silver and platinum. It is not necessary to register the responsibility mark in the country of destination.

Bilateral Convention Switzerland-Italy
Swiss articles with an official hallmark need not bear the identification mark of the importer as required by the Italian act; in exchange the Italian maker's identification mark is recognized as a responsibility mark in Switzerland. Watch-cases with Italian identification marks are not subject to the compulsory official hallmarking.

Bilateral Convention Switzerland-Austria
Mutual recognition of the official hallmarks on watch-cases.

Bilateral Convention Switzerland-Spain
Mutual recognition of the official hallmarks on watch-cases and their accessory parts (for example watch bracelets).

Bilateral Convention Switzerland-Russian Federation
Mutual recognition of official hallmarks by both countries on on precious metal articles of the watch industry in gold, silver, platinum and palladium, eliminate a double control of articles. It is not necessary to register the responsibility mark in the country of destination.

https://www.ezv.admin.ch/content/ezv/en/home/documentation/legal-foundations/non-customs-tasks/legal-bases-of-the-precious-metal-control/international-conventions.html