Ive spent quite a time on this stamp.
Before say anything, please dont count the
lines or columns. It is pointless.
The grill actually goes further, but I guess due to damaged stamp it could not be seen by neked eye.
Howewer, it can be seen under microscope 50x magnification, or perhaps less.
Please check out the photos.
My wiew my be obscured, so, please tell me what do you think about ridges.