What stamp is it? I'd guess from what I can see that it's a 3¢ Washington (Scott design #A46) which was printed by various printers between 1870 and about 1881. The Scott's Specialized catalogue has an alternate value with 'No gum', so I think we can assume that all were issued with gum.
Is you stamp unused (no cancel)? That would explain there being no gum. Otherwise, someone has washed it off. There are collectors who prefer to do that, since as gum ages it can effect the look and value of a stamp.
Your stamp is Scott #207, the re-engraved 3c of 1881. It is not a candidate for any Special Printing.
As for original gum: Your stamp has a cancel. How did they get it to stay on an envelope so it could be cancelled?
If it never had gum then in its day it had to be mounted on its original envelope with glue. Stamps mounted with glue do not come off cleanly. If the reverse is not stained or damaged, then it was mounted to the envelope by its original gum.
Stamp sheets were a bit damp prior to gumming, and when pressed prior to gumming ink is often set off onto the adjacent sheet. Stamps perforated without gum have wretched perforations due to the moisture in the paper - think cutting a damp sheet of paper with scissors. All ungummed Special Printings have rough perforations and are absent from set-off ink. The only exception I know of is #205C, which has distinctively clean perf holes, but I'm convinced #205C was perforated with a stroke perforator instead of a rotary perforator. Study the images of Special Printings and get to know the character of their perforations.