This is a great idea and I love it. Why stop at toning? There is so much we can add to the slab to improve it visually and perpetuate the coins history. I am thinking of starting a slab collectors society where we grade slabs. It would also make sense to refresh stickers annually ( for a fee) and to recheck the toning as it may need regrading up or down. What would be good would be limited edition stickers for say the first toned coins graded. Also categories such as "top population azure", "top population southern hemisphere rainbow", "best chemical enhancement" etc This could bring a whole new dimension to numismatics making the coin irrelevant and save us a lot of money. The slabs could become works of art and as I have previously said there are many who look at the label and not the coin so that would save them a lot of effort simply owning the finest known plastic.
Silver Eagles tone differently than other older coins. Some of them have a questionable look but others do naturally tone. I have seen PCGS slab plenty of the questionable ones but that has not stopped the market from valuing them high. Here are two example that one could call questionable that brought big money at auction. View attachment 1710968 This one I think is more legitimate and it brought over $2k back in 2018
Man, why am I working a programming job like a chump when I've got a bunch of ASEs and a perfectly good oven?