I didn't read the caption of this image I found, but it shows how easy it would be to fake a Nazi Tattoo for the cameras of the allies. The actual ink had a dark blue tint, but the color would have been close enough for black and white film used by the allies.
The yellow print is my own numbers
The tattoo is easy to read and it has no diamond below the numbers.
* Tattoo on the back of the arm
* They use a dash in the number
* No diamond below the number.