I dont have one jerry and never heard of one above fine. Hard to put a price on i would of thought as nothing to compare it with,but definately worth a premium in that grade. How much i think is down to what your happy to pay.
I have heard of this Jerry have you got a picture of a coin that has been treated. Alternatively how can you tell a coin has been treated in this way ,such as colour/tone or any other indicator ?.