It looks like tape used to be on the coin to me but i'm sure Lincoln Cents is right. It's probably due to an improper alloy mix.
i agree it looks like the wood grain affect found on some wheat cents. but it could be either toning or an improper alloy mix but im willing to bet its toning. anything can cause toning it could have been stored in an envelope or it could have been in a chemically reactive environment.it looks eye appealing though cody
Some kind of oxidation, it appears. It would be more attractive if it covered more of the coin. I have seen that in other coins of that era, so it must be something in the composition of the alloy those years.
This is an example of the alloy, copper & nickel that did not mix well and will have the streaking effect....Sometimes it can be very beautiful....
That's similar to a copper "woodie", i.e. improper alloy mix. I'm surprised that it sold for a premium, because this type of toning typically does not carry one in nickel.
Paul can answer better, but I see that type of toning not rarely on Jeffs from the 40's and rarely 50's. IDK what caused it. What does a nice little 40s like this sell for typically nowadays? I am wondering just what "premium" there was for the toning, as the coin is a nice little early Jeff. I don't detest the toning, but don't think its exceptional.
It is not the woodgrain effect seen on cents, nor is it tape. It is actually toning. Toning will form patterns like this. It is not uncommon. There are many reasons for it. It could be something in the planchet composition (like morgandude mentioned), or more likely, it is the way it was stored and what was touching the coin. I have many album toned nickels that show this same pattern. I will be posting some today. Here is an extreme example:
It all depends on the buyer, either they gonna like it or they won't. I still own the 1914 Buff I'm showing and it's a horrible image, sorry. But I won't sell it, I like it to much! If I did sell it I would expect a premium as it's a very eye appealing coin. Some folks hate this type of look.....
I always saw the striped, streaked, toning pattern on nickels stored in the old blue Whitman coin folders. The paper on the back side of the folders always had a habit of crinkling or wrinkling up. So the paper only touched parts of the coins, but it touched them in lines like that on the rev. And then when you closed the folder, they usually folded in threes, the back side of the 3rd page touched the obv of the coins in the 1st page. And that's how you you got that striped or streaked toning on both sides of the same coin.