I've had these for several weeks, but just got around to looking at them. Found this interesting strike through on the Jefferson proof. No, it's not a thread/hair on the coin. Looks like somebody was asleep when this one went through. The other particles ARE dust on the cover. Sorry I forgot to wipe it off before taking the pictures.
I would say that was a hair-like metal shaving, left over from the creation of the die. Someone just didn't do their quality-check very well, when changing out the die. Just my guess.
Oh darn, Frank. Just billions and billions? I was hoping to get at least a Dollar-Two-Eighty for it. My father always used to tell me to keep at least a dollar-two-eighty in my pocket and that NOTHING cost more than a dollar-two-eighty. Don't ask, cause I have no idea where that amount comes from. :goofer: And, looking at it closer, it DOES look more like metal shavings than a piece of hair that was struck through.
Marks like that are often referred to as lint marks. Yes they sre strike-throughs from small pieces of lint or cloth. They are somewhat common on Proofs and considered to be a detraction by most.