In the big picture, "It's all relative."
Dr Gaddy said they don't change.
Abrasion accelerates the removal of the layers. That's why we see color change over time.
This will take me down to 0 stars, but I say they do change.
They are layers of oxides with impurities frozen in situ at quench. Existing in an oxygen rich environment that attacks every other metal that will bind with it.
Some are delicate and relatively unstable, some aren't. And there are literally thousands of those little flaky oxides on the surface. All talking to Oxygen atoms.
Lacquer or oil, keeps the dance floor better separated.
I said relative, because the length of time it may take for us to see a color change may be longer than we can "see".
Another poster some years ago said he saw light damage to colored guns while at Winchester.
He said that the display guns were damaged, or less vibrant, after spending months in the lighted display cases. And he had to change them.
Because the scale is outside of our comprehensions, I have come to believe it doesn't matter. What we see is what they are, to each of our own eyes.
I watched a PBS special on Gems last night. Maybe the previous CEO of Apple ( who has a Ramann spectrometer in his living room for evaluating gemstones) could be contacted about all this.
I think stateside, I'd go with the sure thing. It's going to be sold as a collectible anyway, so use the guy that does every other one. Then that aspect is no longer relevent to future exchanges.
