What does it mean when a coin does or doesn’t receive a CAC sticker?
This is adapted from CAC's own site, and from my personal experience with CAC.
CAC’s rejection of a coin does not necessarily mean that CAC believes the coin has been over-graded by the Third Party Grader (TPG) NGC or PCGS. A coin that fails to sticker may simply be a “C-coin” or lower, where “C” grade indicates the coin is low-end for the grade. CAC will only award stickers to coins in the “A” or “B” category. “B” grade indicates solid (average) for the grade, and “A” grade indicates high-end for the assigned grade. “C” coins, although probably accurately graded, will be returned without a CAC sticker.
Sometimes, in a minority of failed coins, CAC may see things that the TPG missed, such as a light cleaning, a puttied gold coin, a plugged (holed) coin, toned-over scratches, and other imperfections or damage that should have been caught. These coins are not low-end for the assigned grade, they are simply over-graded or should not have been numerically graded in the first place.
The only person that can know why a particular coin fails is the person who originally submitted the coin to CAC. That person has the ability to speak with CAC shortly after it has been reviewed and learn about why the coin failed. A future owner of this coin does not have that ability, nor will the CAC certification look-up tool tell you if a coin previously failed and why. A lack of a CAC sticker should not doom a coin, and a value statement cannot be made as to CAC opinion of that coin. Interested parties cannot know whether a coin lacking a CAC sticker is simply a coin that has not yet been submitted, or is in the opinion of CAC a “C” coin, an over-graded coin, or worse a problem coin.
A coin with a CAC sticker has been independently verified and in the opinion of CAC is either an “A” or “B” coin for the assigned TPG grade. A green CAC sticker does not differentiate between the “A” and “B” coins, it is simply one or the other. However, there is special sticker for clearly under-graded coins. If a coin received a gold colored CAC sticker, in CAC’s opinion the TPG under-graded the coin by at least one full point. This coin is an “A” or “B” coin for the next highest numeric grade, and may even be several numeric grades higher than what the TPG slab lists. Gold CAC stickers are uncommon, only around 1 out of 100 CAC stickers is a gold sticker.
Some of the grading considerations taken into account by CAC include a coin’s luster, eye-appeal, originality of surfaces, quantity of distracting blemishes, and quality of strike. Coins that have unsightly abrasions, market unacceptable or undesirable toning, overly soft strikes, distracting spots, streaks, or other highly distracting blemishes are not stickered by CAC, as these are not “A” or “B” coins. In some coin series, dipping is considered market acceptable, such as Walking Liberty Halves, Morgan and Peace Dollars. In other series, dipping in market unacceptable. CAC takes into consideration these generally accepted practices, but in general coins with original, un-tampered with surfaces are the premium coins that CAC stickers.
In summary, there are three possible results from submitting a coin to CAC:
(1) No sticker, “Not CAC” (C coin or lower, or other)
(2) Green sticker, “Passed” (A or B coin for grade)
(3) Gold sticker, “Exceeded” (under-graded)