Stamp or seal of watercolor (atiributsiya)
 

Good day please tell me whose it is stamped on watercolor and what does it mean?

This so-called blind (or blind) print - print without ink.
In this case, the name of the paper grades.

Thank you very much for your help.
I was hoping, print shop or artist, and then just sort of paper, sadly.

   
" Bristol paper /Bristol pape r" - dense sized paper for watercolor painting and pencil drawings, large-format, also called " paper Isabey ".