Is This A Switzerland 75A?

Agree with Danko. If, despite the odds, you think you've found a rarity, have it certified, especially when the decisive consideration is color: notoriously difficult to identify on older stamps with shades that differ only slightly. In this case, NanoPhilatelic's stamp does look more yellow-orange than yellow, so I can't fault him for asking what others think. The value of this forum is that we beginning and mid-level collectors can get opinions from those who know more, have more resources to consult, etc. And, while I don't think it's fair (or friendly) to assume that anyone who inquires about a possible rarity does so only or mainly because of its catalogue value, highlighting a high catalogue value does give that impression. Better to leave out the money aspect.