Pictures first, discussion after And sorry for iphone pictures, may need to send it out to one of the master coin photogs here. Now, normally if I saw a coin looking like this I would say artificial toning. However, it's a bit different with these proofs. It's fairly common to see proof examples of this type with heavy toning, when the coins had been left in their original case of issue. Usually when I see them the toning is more splotchy, unevenly colored, and/or darker with muted colors. This one seriously pops in hand, with those "oil slick" colors over mirror-ish surfaces. As is expected, the heavy toning is on the "down" side and all around the edge, which made contact with the case material. The "up" side, which was displayed, has only very light peripheral toning. Your thoughts?
As I said before I would think the same if not being familiar with this particular coin. If you do a Google images search with the following keywords - 1966 ireland 10 shillings toned - you will see other examples with wild toning. Also if you search ebay and completed items there are a handful examples of similar toning in earlier stages of development. This just happens to these coins from being in the original case for a long time. The example I posted if just a more severe example, but resents in typical fashion. Like this: http://www.ebay.ca/itm/RAINBOW-TONE...THE-COLOURS-/321804280334?hash=item4aed07a20e This is found on the proof coins, but not the business strikes. The difference being the case they were issued in.
I knew I had seen this coin lately...and just couldn't remember where. Here's mine I just picked up this weekend: (Also in the original packaging)
Very nice! Couple years more in the original case in a warm room and it might tone fully on one side like mine did
