(This section, and the following sections on the counterfeits of the different denominations (including most of the illustrations), are the result of research by Robert Perigoe. This information originally appeared in the September 2012, December 2012 and March 2013 issues of the Journal of the U. S. Mexican Numismatic Association.)

All the counterfeit $1 notes that Perigoe has identified are in Series 3. Only 20,000 genuine bills were produced, so one dead give-away is a serial number exceeding 20,000. It happens often enough that it is a good first step, but usually further inspection is necessary.

Counterfeit $1 Estado de Sonora note Type 1

Est Sonora 1 3 2520

Est Sonora 1 3 2520 reverse

This type is clearly modeled on printing position 3, and is often found in pristine condition. A byproduct is that its picture has adorned a number of catalogues because it is so photogenic, unwittingly authenticating its inclusion in an even larger number of collections.

GENUINE	COUNTERFEIT
The sweep of the printed Randall signature extends beyond the outer frame-line	The sweep does not extend beyond frame
	The numbering device used on the counterfeits is easily distinguished from any of those used on genuine notes because the dot below the ‘o’ in ‘No’ is circular rather than rectangular, and the serif on the top of the ‘N’ in ‘No’ is wider on the counterfeit.
	The shading under the lettering at the top of the note is fine on the genuine notes but coarse on the counterfeit notes.
Regular “P” in left “PROVISIONAL”	The ‘P’ in the left ‘PROVISIONAL’ is broken at its base
Mountain Seal has 18 major rays and diagonal shading in sky and water Shore line slopes up to right	The simulated Mountain Seal is quite crude. There is a total absence of diagonal shading in the sky and water. Worse yet, three major rays emanating from the liberty cap at approximately 10, 11, and 12 o’clock are missing. Shore line slopes slightly down to right
	The small Eagle Seal is quite passable and almost the same type as on the genuine note. It does have the spot between ‘LIBRE’ and ‘Y’, but does not have the broken ‘C’ in ‘MEXICANA’.
Watermarked A.S. & S. LINEN LEDGER	The counterfeit may show the watermark, LINCOLN BOND.

There are varieties with at least three different shapes of colourless area on the breast of the eagle to the left of the snake.