Only ‘Premium Uncleaned Coins' found here.
NRC defines a ‘premium uncleaned coin' by the following criteria:
1) Never pre-cleaned; best is fully dirt-covered, or semi-dirt covered.
2) Centrally struck with legible legends, portraits and reverse details.
3) Exergues/mint marks that lead to RIC attribution.
We do our best to meet all criteria as noted above.
Thanks to Edward Kahler for bringing these definitions to our attention. Kudos, Ed!