Very nice looking knife you have there!
There are/were several "Everts" in Solingen:
Everts, Carl Abr., Solingen
Everts Sohn, David GmbH, Solingen
Everts, Joh. Friedrich, Solingen
However, none of the above were reported as having manufactured or assembled HJ knives. These businesses were more into scissors, cutlery, razors, clippers, manicure sets, pocket knives etc.
In saying that however, the surname is spelt as per the knife in question. But, none of these businesses are listed as being in Merscheid. Garry also mentioned Evertz, Arthur, Solingen. It's possible that it can be spelt differently as Garry has observed, but again, this isn't in Merscheid and the maker marks observed on HJ's from this maker are different to the one shown here.
So, businesses in Solingen-Merscheid ending in "..erts" or possibly "..ertz". And Lordcarnabon believes there is a "C" at the beginning, and I think that is correct as well.
So, we have Kleinertz, Carl, Solingen-Merscheid. But these guys made scissors and the name doesn't end in "erts".
The only other one I could find in Solingen-Merscheid is:
Herbertz, C. Jul., Solingen-Merscheid. But ending in "ertz". They are reported as being a wholesaler and retailer of Solingen and other knives, no production of their own, only assembly. They don't appear to be linked to HJ knives either. But, looking at the pic above, is that a "dot" just after the "C" at the beginning?
So, this is a little mystery!
Regards
Russ