1922 $100 Gold Certificate "Gold Seal Error". 2nd Known Example?
I purchased this interesting note the other day. Since I don't buy these old gold certs often, I assumed the gold seal was normal until further investigation revealed it should be red. I discovered that Heritage sold an XF example back in 2005 and claimed it was the only known example of this variety. The cataloger also mentioned Heritage sold the same note in 1999 for over $10k.
I'm curious to know if PMG or Banknote will authentic this gold cert and make note of the error when grading it. I'd also like to know if there is a way to authentic this error and confirm the paper hasn't been chemically altered to make the seal appear yellow. Heritage's description of their example mentions residual red ink appearing as spots under the gold seal, which my example also has, so I feel that speaks to its authenticity assuming Heritage's assessment was correct. I also wonder has public opinion of this error's authenticity changed in the last 16 years? Does anyone here know if the HA note was ever graded by PMG or another currency grading service? Have other examples been discovered but not sold publicly?
My example (quick iPhone pics):
Link to HA example: