1. In order to benefit from the provisions of Article 1, articles of precious metals must:
(a)
be submitted to an authorised assay office appointed in accordance with Article 5;
(b)
fulfil the technical requirements of this Convention as laid down in Annex I;
(c)
be controlled in accordance with the rules and procedures laid down in Annex II;
(d)
be marked with the marks as prescribed in Annex II.
2. The benefits of Article 1 shall not be applicable to articles of precious metals which, after being marked as prescribed in Annex II, have had any of these marks altered or obliterated.