Peruvian Stamp Sc#25 Without A Grill

I wanted to show you this example of a Peruvian stamp from the 1874-84 issue with a grill. Although the Scott catalog would correspond to an SC#25, this actually appears to be a variety that came out without a grill, which does appear in old Peruvian catalogs, though they seem to describe it as imperforate:

"24 - 10 cts. Green
a - imperforate"
"It is presumed that only 1 or 2 sheets of 100 copies each of error no. 24a existed, whose main characteristic is that it does not have the rear grille."

Hello Muramasa. Isn't that a grill in the bottom left quadrant of the stamp?
Thank you for the information. I was unaware of this variety.

Nothing.. in the bottom left quadrant

Watermark test the stamp. Grill points will look like a series of dark or thin spots Ii present.

I'll try it, but really in the rest of the issue the grill is very pronounced and clearly visible