Help! 12x10 Perforation 1914 Usa423B George Washington Type I Possibly?

Hello. we recently inherited a stamp collection and have been going through them for the past few days seeing if there are any of value.
We think we may have stumbled up on an EXTREMELY valuable stamp. So much so that we are feeling completely out of our depth and need a sanity check.

Based on what we can find online it appears to be a
12x10 Perforation 1914 USA423B George Washington Type I

Everything seems to line up and we just need someone to guide us on what we should be doing here.

Thank you!

Short answer: No.

Longer answer: Perforations are gauged (as in a rate per 2 cm), not counted or figured in some other way. Your stamp is "perf 11" on all sides. The shade also indicates it is printed by the "offset" method, thus can only be Scott 526, 527, 528, 528A, or 528B.

The stampsmarter.com website or the "Scott" catalogs typically available at your local library are good places to start.

John,
thanks for your reply.

I did some cursory searches of the types you listed and I can't seem to find any that are only perforated on 3 sides like this one. Also, the colors don't really seem to match up.

We have around 20-30 other stamps 'similar' to this one but the color of this one is very noticeably different. So is the shading/shape of washington.

Would you think that this is worth bringing to a professional to have a look at?
Even the types you listed seem to be valued unbelievably high so I'm kind of in shock here!

We're not stamp collectors by any means but if it's worth the trouble we'd like to make sure we have it analyzed thoroughly.

Knighted - Your stamp is Scott 526, Type IV, Perf 11, offset printed.

That is exactly why I know it is an "offset" printing. The color/shade is indeed distinct. Your stamp is "used" so the value is actually quite modest, and with the poor centering, crease at upper right, and straight edge at left, the retail value is not more than $1, whichever of the 5 types it turns out to be.

Straight edges: This particular printing was done in press layout of 400 impressions, cut into panes of 100 for retail sale. There are natural straight edges on two side of each pane of 100 (read that as stamps along two side of the retail pane will be perforated on only 2 or 3 sides) thus on 76 of every 400 stamps made. While slightly scarcer, they are less in demand, as thus have a lower retail value. (Plus there is some possibility your stamp was trimmed on the left side after sale, thus damaged.)

Two problems here. First, you must be looking at mint never hinged prices ... and even then the most valuable of the types mentioned would be about $115. Used copies max out at about $4. Second, the catalogue values are for VERY FINE (grade 80) stamps. Your stamp would grade no higher than 50 (VERY GOOD). Grade 50 stamps generally have a value of roughly 25% of their grade 80 counterparts. So the specified value of $1, while probably generous, is reasonably accurate.