This above is genuine, mint 4-block of Sun Design 1919
Read more about Sun Design here:
This above is a genuine Sun Design stamp. A very thin "cigarette paper" was used when printing the Sun-design stamps. Later on the Tallinn Skyline stamps were printed also on the similar, very thin paper.
The next four items are:
These are very easy to detect; just focus to the middle sections and you will see easily the differences with genuine printings. And remember, there are only these 4 different types which Jaan Lubi used in his forgery-work.