11 perferation on 2 sides adjacent
Thank you for contacting Mearto with your appraisal inquiry. Based on the photographs and description provided, the subject of this appraisal is an unused, previously hinged, ungraded 1 cent Benjamin Franklin green United States Issue stamp circa 1927. The stamp was printed as one of the far right stamps on a sheet. The condition is estimated at Unused Average based on centering issues and a hole in the stamp.
This issue stamp was quite common during its day with some very rare exceptions. Unfortunately, photographic examination without a precise stamp gauge and different reference measurements including color makes identifying this stamp as one of the rare issues impossible. Based on color alone, however, it seems this is not one of the rare issues.
For an extensive writeup on the rare Franklin vs. common issues, please refer to: https://www.linns.com/news/us-stamps-postal-history/2015/january/is-your-1-green-franklin-stamp-scott-594-or-596.html which includes pictures of different varieties. If the stamp in your possession truly measures according to the guides that would have it either a Scott 594 or 596, it is highly recommended that the stamp be graded professionally, then appraised.
It is most likely based on its yellow-green color that this is actually a Scott 632. Simply put, you can't just count the number of holes on a picture and translate it to a 11 x 11 perforation stamp. Measuring stamps and identifying a truly rare issue does require a precision measurement with precision gauges.
In consideration of the factors noted a Fair Market Value (pre-auction estimate) of this piece would be estimated at approximately $1.