Hello, everyone. As I've stated, I'm relatively new to coin collecting. Could you all tell me what to look for when trying to determine if a coin has been tampered with in any way? What should I look for when evaluating a coin that I have my eye on? Are there reliable methods used to determine whether a coin has been cleaned or polished? Also, does the lack of luster on a coin that is, otherwise, in good condition significantly lower the value of or bring down the potential grade of that coin? Any help from you seasoned experts would be greatly appreciated.
Consider taking an introduction to grading class at the ANA summer seminar (www.money.org). Also, NGC and PCGS offer grading classes at some of the larger coin shows. I believe NGC recently advertised a class at an upcoming central USA show. One way to hone your grading skills is to attend shows & closely inspect graded coins. You will find the coins that have been harshly cleaned & polished are either labeled as such or not in slabs.
When dealing with a coin that is not encapsulated in a third-party grading service holder, there are numerous ways a coin can be tampered with to artificially increase its value to an untrained eye. Even some of the third-party grading services can encapsulate problem coins without noting it on the label, this generally doesn't occur with the top two third-party grading services (PCGS and NGC). Here is a rough guide of what to look for: http://www.ngccoin.com/coin-grading/coin-details/ That list is a good outline, but lacks depth. It's a good place to start, though.
You might search for previous threads at CT describing technical grading & market grading. Yes, a lack of luster on a coin can lower the market grade/value of the coin. Of course, attractive luster on a coin can increase the market grade/value of the coin.
Forgot to add, a good place you can look at such coins quickly (albeit not in person) is eBay. You'll see a variety of coins not in third-party holders that look suspiciously shiny, or have some details a bit deteriorated at a rate that doesn't correspond with others nearby, etc. Search for "NGC Whizzed" or "PCGS Whizzed" and look at the zoom-in images of some of the coins you see. With these, the seller isn't trying to hide the fact that they've been improperly cleaned. It's the coins not in third-party holders listed on eBay that often have issues that can't be seen without magnification, and certainly not online. At a coin show, you're free to examine potential purchases with a loupe (I find if a dealer won't let you look at a coin under magnification before purchasing it, he's probably trying to unload a problem coin on you), but don't have that luxury online.
Being able to correctly identify a problem coin is one of, if not the hardest thing there is to learn in numismatics. There are virtually books on the subject, none I ever heard of anyway and very few articles on the subject although many articles will mention it. The only way there really is to learn is by experience. You simply have to look at many thousands of coins and discuss them with others. So if you really want to learn pic a coin, post some pics, and we'll all talk about them
