Well, since the Gold UHR is supposed to be .999 gold, that would mean that NCS would burn off .001 silver and sulfur. Would that leave me with a coin that would be 100% gold? Would it also make the coin that much lighter? I'm not sure that a lighter UHR would be considered a truly minted coin, perhaps one that was well counterfeit.
Well, I have to see more evidence ( any evidence) before I accept that hypothesis, but if it is true, it would only be off of a small mount of surface, so the internal mix and weight would still be within tolerance.
Was trying to be funny, guess I didn't succeed. As to evidence, there's a photo of coin on page 4. This site allows us to blow it up and it shows the silver spot very clearly. It's in the rays directly below the center of eagle and above the letter W in the word We. I loved the letter from NGC recommending it "might" be a good idea to have NCS take a look. I guess I must alter the coin surface to improve the coin. I'm torn between renewing membership and continuing collecting certified coins or just buying from mint to place in my own protective slabs. As to value, the percentage of value growth (if there is any), seems to be about the same. It's quite expensive to collect certified, especially if you're a true collector that just wants 1 coin to add to a series. If you send it off and it comes back a 69, you've actually lost money (except with gold).
Gold is not inert. Looking at where it sits on the periodic chart and remembering chemistry class it could combine with other elements or compounds. However, what those are would be limited. I'm gonna talk to my friend who is a professional chemist that works on Titanium and see what he thinks. By the way, he informed me that the pretty Titanium you see in Jewelry is the stuff they can't use because it has lots of impurities. He informed me pure Titanium has a rather dull look.
Getting way off track and I'm no expert but found this, you may be interested: :In addition, gold ores are processed with oxidization with "King's water" (3HCl+HNO3 ) and treated with cyanide, afterwards reduced with zinc rods; so very pure (up to 99.99%) quality gold can be prepared. As imabug said, gold isn't oxidized, since it is an inert metal; you hardly prepare a [AuCl4]− complex and can easily reduce it to the metal with elemental potassium, etc. :
I purchased a 99999 coin directly from the RCM and sent it to PCGS with true view service. Now the coin has several small red around the rim. as you can see from the true view image there were no spots when I sent them to PCGS. any comments are appreciated