I agree w/Beef who posted: "An AU coin won't have the full [ORIGINAL MINT LUSTER] luster like an MS coin would have." baseball21, posted: "58s still could. The 58 grade today is a really nice coin that has a touch of rub." Nope. An AU-58 is no longer Mint State. It may look MS, it may have more eye-appeal than many MS coins, and it may be priced higher than a true MS coin; but it is not a Mint State coin. Some confusion occurs because many folks consider the word "luster" to only apply to the original mint luster seen on coins with no friction. Areas of friction, unoriginality, and alteration on a coin's surface still reflect light (luster) - it just looks different than the reflected light (luster) from a natural surface.
The old old time dealers called them "sliders" as they were circulated but could "slide through " to MS.
Thank you all so much for your answers! I have one final question, can a coin be concidered UNC when it has a few scratches?
Yes...MS starts at 60...from Jason Poe's book "The Art and Science of Grading Coins": "MS-60: below average to average luster and color, numerous severe contact marks, obvious mistreatment, below average eye appeal". You may want to check your local library to see if this textbook is available...I refer to it often. Best collecting to all!
I'm pretty old and what I recall was calling them "sliders" because of one of two reasons. The first, and oldest was because many old time collections were housed in cabinets in velvet lined trays. The coins slid around when the drawers where opened and closed and the coins suffered impaired luster on the very highest points. Second, and more recent, say, 1960 and up is that the coins were kept in albums with plastic slides that put fine scratches or wear on the highest points when they were slid in and out of the page.
And if a coin has wear on it when it leaves the mint - what then ? And make no mistake, more than few of them do have wear on them when they leave the mint. And that's just one of the many, many, reasons that the definition of an uncirculated coin is a coin that has no wear. And that is the only definition there can be. Yes. That is because scratches do not qualify as and are not wear - they are merely scratches.
That's a very good write up of mint luster. Just to be clear on the distinction between MS and mint luster... Mint State would also need to take into account other types of damage, as you'd still have very strong cartwheel luster on many AU coins. For instance, wear on the high points of a coin with "perfect" mint luster everywhere else may yield < MS grade, depending on severity. Then you have the excessive damage to otherwise uncirculated condition coins with brilliant mint luster, which TPGs would assign a Details grade.