I have a NGC graded AU58 1935 Washington quarter with tonning. I was wondering what it's worth with tonning back is beautiful the front have rainbow tone but mostly brown.
Looks simply like an album toned quarter, whatever greysheet lists them at. I do not see anything special about the toning.
While it's true that many toners sell for decent premiums, there is no way that anyone could tell for sure what this coin might be worth based on those photos. Chris