I have an 1880-S which has a lot of luster, but I chose not to grade it due to a gouge in the reverse. After closer inspection today, I think the gouge might actually be an error. My best guess is a sliver of material fell on the planchet when the coin was struck, and both the coin and sliver deformed. Then later the sliver fell off, and what was left is a dent with the letters raised inside of it. Does this seem correct? Is this an error at the mint? Does it add anything to the coins value, or take away by ruining its appearance?
This is a possibility. I see no raised metal around edge that is evidence of Post Mint Damage. Struck-Through Metal Dust or Shavings. http://www.error-ref.com/struck-through_metal_dust__shavings/
It would be better if you had the missing lamination. At some point in it's life, looks like someone removed it. Nice photos by the way.