I have what i believe to be a a sintered planchet on thus 2018 D jefferson nickel .The coin in question has original mint luster but with weakness on the reverse .
In my honest opinion, that's just toning. Environmental exposure toning. Not a sintered/Improperly Annealed Planchet. If it were sintered it would be even on both sides. Here are 3 I Metal Detected yesterday..
I appreciate your insight , you are very knowledgeable as i have been a reading member for a few years now and you always seems to have an abundance of information. My camera phone may not represent the coin in it's most natural way but will take your opinion useful and add it to my growing bank of knowledge, thank you !
You're welcome. Here's a great example of an Improperly Annealed Planchet in a Nickel. From my collection.