gmims,
starting with the 1908 printings (Scott 73-87), the postal authorities decided to coat the face of the stamps with a vertical varnish network of lozenges to avoid washing off of cancellations and re-use of stamps. This network consisted of intersecting diagonal lines appearing as a pattern of (largely colorless) rhombs above the stamp design. The width of these varnish lines is between 0.75 and 1.5 mm.
The varnish network is visible in glancing light looking at an angle of 45-60 degrees. Printings of these ruble values after the Revolution have this varnish network applied horizontally (Scott 87g, 137b, 138b or their imperf variants: 87h, 137d and 138c).
I would say that your stamp is a Scott 132 (with a vertical network), but it is worth checking for the rare horizontal network one. Mind you, in some cases the varnish network is not easliy visible (not to talk of those cases where it has been omitted by error).