Recently, there are a lot of fakes on the market, especially with various specialties like inverted or double overprints. Below are the two most common types of forgeries...
Genuine overprint
Sharp edges and homogeneous structure of color are the most important features of the genuine overprint.
Forgery A
The wavy line in the middle is not thinner. Upper curvature of the letter S in Yugoslavia is more angular and facing down.
The wavy line in the middle is not thinner. Upper curvature of the letter S in Yugoslavia is more angular and facing down.
Dotted structure shows that this forgery was the most likely made with a conventional laser printer.
Forgery B
Star between 9 and 5 is like a rounded stain. L in Yugoslavia is not perpendicular and facing down. Both A in Yugoslavia are without a dot.
The edges of the overprint are not sharp enough and sometimes color spills out. This is typical for a rubber clichés.
