I've been using This picture from beersmith.com of a refractometer (Looks like the same refractometer as mine) scale to go back-and-forth between my brew notes (at the computer) when doing ABV calculations. I sometimes record the SG reading during the brew because I'll have the target OG of the recipe in mind and just not "thinking" in Brix.
Today, I noticed the scale at beersmith and the one in my refractometer (pic below) are not the same! Shouldn't both just be representative of the mathematical equations to convert Brix <> Wort SG @ 20C?
Other than a crummy QC process at the factory, is there another reason these two scales would be so wildly different (eg: compare at 16 Brix and then again at 29 Brix)?