2008 Silver Proof Quarters

The only thing I can think of is Toning - seeing how these are contained in a jewel case it shouldn't be from being touched, however these cases are not air tight, humidity, and possible storage issue can contribute to this.

Just a thought, Maybe some type of devise is used at the mint to press the coins into the holes and that devise had some containments on it?
John1

The Haze/Cloudiness is related to the environment they were stored in such as moisture/humidity and temp. Sometimes the outer coins or top sets of coins above others below likely take the 'hit' unless all coins are exposed. NCS (NGC) conservation services can restore those foggy coins but this is not worthwhile value wise for many, and milk spots are different issues. I'll play around with it eventually, but some positive results have been shown from using EZEST, the key is diluting to 1/2 EZ Est 1/2 Distilled water or even 1/4 strength EZest. Another key is to be quick with the dipping, perhaps 2-3 seconds only then rise with pure distilled water. Anything more than that will start to ruin the surface which is where most likely gave up, so perhaps a little practice on some bullion that has no premium value would be a good start and then can move on to those pieces with value. Milk spots on the other hand apparently wont work by that method once they have settled in.

Hi John1, Coins with a purity of 999.0 or higher can frequently develop the milk spots, which can be found on both bullion and Proof finished coins. However, seeing these spots on older coins with alloys is uncommon. The exact cause of milk spots is not fully understood, but it is believed that one reason is they may be formed during the manufacturing process. For example, during minting and annealing, chemicals are used to clean and polish the coins. If these chemicals are not properly removed/rinsed off, they can react with the metal and cause the formation of milk spots later on when they react with the environment.

The Royal Canadian Mint developed a tech called Mintshield which is a transparent protective layer applied to the coin's surface during production, creating a barrier between the metal and the environment. This tech is used also by Perth Mint who took added steps to try to prevent them from forming. They have implemented a new cleaning process that uses ultrasonic waves to remove any residual chemicals from the surface of the coins before they are packaged and shipped.

So I am just thinking that once reactions start it appears possible to reduce them or stop since there was progress made by the conservation, but they cant yet eliminate them without damage so that suggests once they 'settle' you will likely be unable to do much with them. In other words more like the fingerprints where you can perhaps do something immediately, but not after its 'settled' is my thought. Of course haze is a different issue and appears able to fix such as early proof sets.

Here's similar effect on a 1974 Ike. I put it next to a 71 so you could better see the difference. The coppery color is not quite as prominent as your AZ quarter. Maybe a different reason due to the differences in composition.
I don't have notes but I'm pretty sure I broke these out and soaked them in Acetone at one point within the last year.

Just Checked My 1996 Through to the 2010 Silver Proof Sets, Not a Single Coin, Not a Single Set Looks like the OP's Pictures, All look like they were Freshly Minted Today !!!!.....
The 2009 was an Extra Fat Package Too ....



PS, The KENNEDY'S look Amazingly Fresh Too.....

yep, re-checked mine - all look great! and BRAND NEW!!