From NGC site...
Unfortunately, not all coins can be numerically graded on NGC’s 70-point grading scale. This includes coins with detrimental surface conditions that result from exposure to extreme environments or mishandling, either deliberate or unintentional. However, these coins can be authenticated and have their conditions consistently and accurately described using precise grading terminology, NGC Details Grading.
When certified with NGC Details Grading, each coin is first assigned a details grade that accords to the amount of detail present on the coin. Coins lose detail as the result of wear, which is metal loss that occurs during circulation. The coin’s details grade is then followed by a description of the surface condition that makes it ineligible for standard NGC grading. These descriptors include such terms as CORROSION, SCRATCHES or ARTIFICIAL TONING. A complete guide to the terms used by NGC Details Grading will be available at
Third-Party Coin Grading | Numismatic Guaranty Corporation (NGC)
Beginning September 1, 2009, all coins that exhibit detrimental surface conditions submitted under any of NGC’s grading tiers will automatically be graded and encapsulated using NGC Details Grading.
This service is provided automatically at no additional charge. Submitters may elect to opt out of NGC Details Grading, but full grading fees apply to all coins examined, regardless of whether or not the submitter chooses to have them encapsulated. Concurrently, NCS encapsulation will be discontinued.
