Official Proof Identification Help

I was able to pick up this pair of what I think are plate proofs on card for a song on ebay. The 1c (O35P?) is slightly thicker than the 12c (O41P?). Since I'm not well versed with these, can someone speak to the different thicknesses and colors? I know my Specialized catalog mentions this but the difference in colors between these two is dramatic. Thanks!

The 12 cent is ultramarine, the issued color. It might be a bit faded though. The one cent might be a trial color proof in blue, based on the scan as I see it. Or it might just be a darker shade of ultramarine; tough to say from a scan.

The variation in color is quite normal for these. I have the complete set and the shades are all over the board. The proofs on card are a nice cheap option for these since they are less expensive than the stamps. I believe the majority of them can be had for $5 - $10 each

Here are a few of the different shades.

The differnt shades are the various printing of the plate proofs on card, something like 6 differnt printings. Not positive but think I read that the Bureau of Printing and Engraving printed the 6th set. I've been read The U.S. Philatelic Classics Society "Web Chronicles" specifically the Officials sections and there doesn't appear to be any way to tell the differnt printings apart. If you're interested, I can email you the index to the Chronicles that I copied/made.

Once again, this is great information, thanks so much. I have quite a few plate proofs in my Officials collection, and for the Officials I think I'm going to gravitate towards the proofs. They do seem to be quite reasonable in price. Littleriverphil, thanks for your offer, I'll send you a message.

You'll find quite a few more variteies of double transfers, foreign entrys, and plate scratches on the P4 proof ( Card Proofs ) than on the India paper proofs. Most of the Official stamps were printed on sheets of 100, and there was only the one plate of each stamp, every time it was used was another chance someone could drop a tool. Don't forget the Atlanta Trail Color Proofs, a little more expencive but worth it.