Yay, Found A Special Printing!

Albeit with a crease and gunk at the bottom, but a 211b nonetheless!
The guides mark the distinguishing factor as the cross-hatching that fades away under the chin, but isn't it visible because of the quality of the strike rather than a design change?
Other areas such as the horizontal lines above the head are clearly separated and tight, rather than the gunky feel of a 210.

*Edit* The one on the right, and the first closeup picture is only for comparison.

Or not …

As I recall, there are no known used 211B. You might want to check the PF certificates (www.philatelicfoundation.org) ... they have 5 used stamps that were submitted as 211B. All were determined to be 210. My point is that finding a used 211B is highly improbable. I am no expert, but I do know that many 210 are misidentified as 211B. In any case, if you become convinced that your stamp is indeed a 211B, please have it certified by one of the expertizing groups .... PF, PSE, PSAG, APEX.

Thanks for the link!
Absolutely this is it. Not only in the details, but even the margins are a bit larger than the 210.
It's not near as elusive as it's 4c brother, but there were plenty of these made so it's not like a jackpot winner or anything.

It's only like a $200 stamp (if that bc of the faults), so I don't know if it's worth certifying?

Not a chance that the OP's stamp is a 211B.

This is a 211B. Note the crispness, clarity and separation of each line. Don't waste your money sending it the example in this thread in for a cert.

It's in mint condition. Of course it's crisp XD

The picture above is from philatelicfoundation.org, and looks way closer to what I see on Seigel's than the one you show here.
No offense. I know you know a lot more than me, just stating what is shown and why I even posted this here in the first place.

And that one seems to be faded, and kind of dull.
The 211b's I've looked at seem like old photographs more than a stamp. That picture just looks like a stamp.

Stephen - Do what you want. You are obviously treasure hunting. Be prepared for disappointment.

This is not going to end well, so let's move on...
Don