What type of error is this? The serial number and the Dept of Treasury Seal was inked so hard, you can see the light green color on the back side.
That doesn't look significant enough to be an error. If it were more solid then maybe but definitely If it was actually printed on the back!
what you are actually seeing in this case is "embossing" the immense pressure used in the printing process causes this. You may see on some third party graded material "exceptional embossing", this is what that is. I would not consider this an an error by any means. jaf
If there's nothing else special about this note (gem unc, B58591699D) would it be considered a keeper? Thank you all for your input.
I wouldn't expect anything over face value, but if you like it, then keep it. Personally, I'd probably keep it just because it looks like a great quality note and it is only a dollar...