Actually, I am that fellow collector. Many thanks to Paja, who was kind enough to publish this item here.
I have found it in France, and the previous owner didn't known what that actually is. As a collector of Serbian and Yugoslav orders and medals, I am not so familiar with imperial Russian artefacts, but, there is some dirt inside of central medallion, as well as under the magnifying glasses, all marks appear to be in line with all I could find online. There is Moscow ,,Kokosnik" sign with number 84.
As I am new to this wonderful forum, I will try to uploade some additional pictures. This appears to be quite rare badge as this infantry unit existed only for few years. Maybe it's a wartime production, which could be the reason of strange enamel ( but without any trace of modern touch)
All comments are more then welcome, as well as helpfull.