toned 1956-1964 ?Blue Toned Nickel Mystery? 0

[couponschevette]

A coin that has hooked my interest is the wildly toned blue Jefferson proof nickels? But what causes this wild color toning and its so often deemed as Artificial toning but major grading companies deem it as real? And to what leads and feeds this general distain and idea that something with such crazy color has to artificial? It could be something in chemistry but why is this so uncommon are so vibrant?

I have graded and am currently grading 9 coins that range from the years 1956-1964 and follow from PF64-PF67 and was looking for community input on what may lead to this mysterious color.

 

[Coin Cave]

Whitman made blue coin folders in the 1960's.  I have seen one that housed Mercury dimes that turned some of the coins blue.

[VKurtB]

These are absolutely real. I have always believed it is something in the pliofilm that causes the coloring. The most vibrant I see are the 1962's. Some 1960 and 1961 proof nickels tone a yellowish green.

[Weidel Legacy Collection]

I've attached images of a '62 proof I found in a set purchased 4 or 5 years ago then submitted to our host - it came back PF68 UCam. The images don't do the coin justice as it is a gorgeous blue and purple on both sides with deep dark mirrors.  I was disappointed that it wasn't deemed star-worthy 

Over the years I've found a number of raw proof nickels still in their plastic sets that range in color from green to red and definitely believe they are all naturally toned.

[Coin Cave]

That's a nice proof for 1962.  

[Weidel Legacy Collection]

Thanks - when I saw the set with no premium for the nickel I couldn't pick it up fast enough!