Having just sorted through my collection of stamps and letters of the German inflationary period, and scanned a large number, I thought it interesting to show the complete series I have, with the Michel tables in English, in order for people to better evaluate their examples.
There are many references and excellent features on the inflation period here in Stampboards so I am loathe to compete however, I think an examination in detail of the era with examples of variants etc, would value add a great deal.
So this is for beginners in the area as well as more advanced collectors. I hope it generates discussion, particularly when I get on to the postcards and letters of the period. Hopefully it will answer the more simplified questions often sent as well as stimulate some argument on more difficult stamps.
I am putting 5-6 scans only for each posting. They show examples of all postage stamps issued and that might have been used from the period mentioned in the title. Where appropriate I have examined some features of stamps in more detail. I then move on to the postcard and letters of the various postal charge changes throughout the period.
Please try and ignore my pencilled annotations, I have a well thumbed and used copy of Michel in English.
Note. In Tables following a,b,c etc denote shade differences.
I and II denote differences in crown cross and script. I features an absence of a cross, II shows a normal cross, as shown below.
** Never hinged mint (NHM)
* Hinged mint (HM)
Circle with dot = postally used
Letter sign is general value for any printed matter (examined in detail later).

Table 1. Michel English list Jan 1920 to April 1921.

As usual determination of colour is a problem particularly with cancelled (used) examples. Expertisation is recommended, but even here I have examples where there are large colour differences in what have been designated the same variant! Also computers can never reproduce the conditions for best examining the stamps.
As mentioned by many others, the cancelled stamps are valued much more highly as CV than mint. This gets worse as the window for the use of the stamps was shortened in the hyperinflation era. Most of the cancels are regarded as false and used stamps are best valued after expert.
Figure 1. My page showing Michel (Mi.) 140 to 153 (plus four 1921 stamps dealt with below)

Figure 2. My example the 3 Michel 140 shades all signed as genuine.

Figure 3. My examples of signed Mi. 142 shades.

Figure 4. My examples of signed Mi. 143 a and b shades.

Table 2. Plate flaws.
