Lamination is when flakes of metal being to peel or flake of a planchet do to impurities in the alloy and this can be attached or detached. I can be as small as a pin head or almost as large as the coin itself, and is easy to identify since it looks like metal leaf when attached and grainy if detached.
Slight laminations on common Lincoln Cents or nickels do not add much value to a coin because they’re common, but values increase on type coins, silver then gold coins and in that order. Value factors depend on grade and date as well and can be anywhere from $50 all the way up to $1,400 for a $20 Double Eagle.
Image courtesy of Heritage Auctions