The only mark on the blade is ‘Inox’. Is it stainless steel or not?

It is a common myth that stainless steel can be tested with a magnet.

A magnet will stick to every stainless steel item in my house, including all the cutlery and the kitchen sink.

In fact, there is no one substance called stainless steel – it is a whole family of alloy steels. Any steel containing 10.5% or more chromium can be described as stainless.

Nickel is frequently added to the mix, too, to further enhance corrosion resistance, and as the proportion of both elements in the steel increases, so magnetic qualities decline, eventually to vanishing point. Cutlery grades of stainless are generally magnetic.

The ‘Inox’ marking on your blade is a contraction of the French ‘Inoxiable’, and is a common marking on stainless steel items manufactured in French-speaking countries or made for the French market. The German equivalent is ‘Rostfrei.’

It certainly seems that your knife is the genuine article.