I collect U.S. Mint Silver Proof Coin Sets (MSPCS) and had ordered from an online dealer one of the previous year's MSPCS; I noticed that the dime had a ""copper"" looking blemish which lead me to research available services for coin valuation/authentication. I found Excelsior Coin. Unfortunately, my first and only visit was met by a grumpy, uninformed, unfriendly, and opinionated woman (whom appeared to be the wife/co-owner of the business). I asked her if a coin blemish such as described above would affect the value of the coin. She looked at me and said ""What do you mean?"". I explained that I had bought the MSPCS and the dime arrived with copper spots. She looked at me like I was from another world and flat out said ,""No."" (The U.S. Mint website itself had a link describing how the look of a coin, including any blemishes, WILL AFFECT its value). I further explained that the coin was only 2 years old and I couldn't see how a 2 year old, uncirculated coin could ""naturally"" blemish AND not be devalued. She replied that, it just happens and that, no, why would it affect the value; it's sealed and there's no reason to think the value would be affected. (BTW, the cases can be opened and reclosed). I remained courteous, perhaps too courteous, and even showed her the coin set I had brought with me. I then asked if the dealership offered numismatic services to which she asked ""What are you talking about?"". I explained the advice of U.S Mint. She then said, ""Why would you want that?"". I replied that I was looking to have my coins evaluated for value and authenticity. She glared at me from above her spectacles resting on the tip of her nose and replied ""That costs money"". Please :). I was pretty much done at this point, actually I was done beforehand but, like most good citizens, I give people the benefit of the doubt. Even grumpy old people, and she was very grumply, cold, had poor knowledge and terrible customer service. My advice: Go only if you are very desperate.
Pros: Not a lot of local coin dealer competition so this is an option if desperate
Cons: Poor Customer Service, Not Helpful