Hello Detlef,
Why I do believe even more so it is silver?!
OXIDATION!
Please notice that the depressions/crevices in the engraved metal are oxidized black, which is quite typical for silver. Nickel-silver does not oxidize like that (see your example).
PS: Silver is very easy to identify without any effort other than patience. If in a few months it will start developing darker oxidation, then almost certainly is silver. There are also liquid reactives for identifying silver and any jeweler will be able to identify it immediately.
PPS: From the photos, it appears the hanging loops are not the original but replacement ones (different metal and crude fitting).