2001 Washington quarter buried or PMD or bad lamination. Looking to learn the differences between them.
Unfortunately, this coin has been damaged. Also, being buried would be a form of PMD; PMD is just damage that happened to the coin after it left the mint. To help you understand what a lamination is, read about laminations here: https://www.error-ref.com/part-v-planchet-errors/
It's a stain of some sort. A harsh chemical affected the Cupronickel clad. It caused the copper that's mixed with the nickel to tone a darker color.
