How to check a supplier's certificates

A certificate is issued by a third party after they test something. A declaration of conformity is signed by the manufacturer taking responsibility themselves. Both are legitimate documents, but they are not interchangeable, and a logo printed on a product page is neither.

Ask four questions of any document: who issued it, which exact models it covers, which standard it is against, and when it expires. Most sourcing problems come from the second one — a document that covers a model close to, but not identical to, the one you are buying.

Check the scope line too. A quality-management certificate covers a defined activity at a defined site, and that scope may be narrower than the product you are ordering. Read what it actually says rather than what the logo implies. We publish our own ISO scope on the Factory & Quality page for exactly this reason.