Germany, Allied Occupation

They are different stamps of West Saxony.
I think they are: Michel 117Y, 117BXb, 128Y and 121X.
The only question is that top right stamp have violet-red color?
The other stamp have violet-grey color.
Thank you for posting the two colors (if you have) for see the difference.

I don't have the catalog in front of me but the lower case "b" in the expertizer's mark "BXb" represents the color tone.

Unfortunately it is not an expert mark. The name of the expert does not appear.

From a scan I can tell red from blue, but when it's a matter of distinguishing hues a scan isn't really good enough, is it? So although an opinion here may seem to help, doesn't one really need to view the actual stamps in natural light? (Even then I often struggle.)

cupram,
I have had more time to look at your stamps. The 117BXb catalogs 2400 euros ** and approximately 60% of that for *. The designation "BXb" should read vertically down on the left rather than horizontal as shown, which makes it a little suspicious. I would not buy this stamp without a current Attest.

The LL stamp cannot be 128, that would be the 5 Pf stamp. It also does not appear to be perforated K13:12½.

I would carefully check the perforation measurements on all 3 stamps.

Thank you germania,
I was wrong,no Mi#128Y,it is #121Y (private perforation L10 3/4 not registered by Michel)
I have these stamps.The inscription on the back of the stamp drew my attention to the color. I do not think it is written by the expert.
I want to know if it is appropriate to send the stamp to the expert.

Another set of Mi#117 made in sun light:

Doesn't anyone have the 2 colors to post them to see the color difference?Thank you.