I had heard of spark erosion before but never used in this area. Just be aware and carefull, articl is below: http://www.pcgs.com/articles/article2630.chtml
I'll tell you, with stories like this, coupled with cleaning, whizzing, etc, it is enough to scare most casual coin collectors out of the hobby. It really is a shame that you have to become an expert in order to protect yourself. There are some great coin value resources out there, but unless you are a proficient grader, you really are at the mercy of the person suggesting the quality. I have read posts on other boards that say if you bought a raw coin and got the raw end of the deal, it is your own fault for not being what amounts to be a professional grader. This gives the impression that many coin dealers are looking for the unsuspecting person to unload their junk. Since I am not afforded the time to become an expert numatist (?), I have started to look exclusively at PCGS/NGC slabbed coins. They might not be perfect in grading, but they certainly do a better job than myself. It is like paying extra for insurance when shipping a package. Not to mention it is easier for me to sell on ebay if I start to change interests. I have passed up several beautiful looking raw coins that seemed to be good deals, but this is exactly what you become suspicious of. A good value on a PCGS slabbed coin is a much safer bet to the average person if you ask me. It is unfortunate that the coin hobby is so tainted. This is just the thoughts of a new member in coin collecting.
Good thoughts for all of us. I have been collecting, trading, and selling for 30 years and what I percieve as an XF maybe an AU to the owner and or vice versa. I prefer to buy in person and have found out if a dealers first price is his only price with no consensus I find another dealer I left a post earlier about the Collectorama in Lakeland Fl this weekend. I bought 3 high grade Ikes from one dealer at $1.65 each excellent price for full BU's,but at another dealer he wanted 2 bucks for F to XF Ikes same year I passed and he lost a sale. I will say this the dealer who sold me the 2 BU 72's for a 1.65 each didn't do his Ike homework.
