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So, following the diagram above, the OP's experiment failed because not all the coins changed color.

The answer to the question "Does MS70 turn copper blue" is therefore no.

When we ask "Under what conditions do copper coins turn blue with MS70" then we get to the truth. The only group of coins that turn blue are coins with some kind of coating on them prior to the treatment. This is a subset of all coins with coatings. Coating are dirt, debris, lacquer, shellac, etc.

Next question is "why do they turn blue". Here there is no straighforward answer because there are a multitude of coins with vastly different histories. I know that there were hoards of Proof Indian and Lincoln cents from 1878-1916 that are blue-toned. They came on the market in the late 1930's. These got blue toned by sitting in envelopes for over 50 years. Eliasberg had some in his collection.

The simple answer is that the toning was always there, but hidden by surface coatings. If you want to disagree, use the chart above and prove it. Just saying you saw the sun rise when the rooster crows isn't proof.

In the OP's example only the dark coin turned color. It had finger oil on it from circulation, as most copper does. We are not used to seeing the copper stripped of its naturally accrued oils. Bright red coins don't have debris on them, so there is no toning being covered up on them. Only the dark coin turned color. Is that toning artificial or natural? I would say it is unusual.

I hate to hear this! Mike was a friend and a good mentor. I always ran purchases by him in the Barber series before forking over the money. In fact, I had just asked him about one a few weeks ago. He will certainly be missed. He always like this coin of mine, so I will post it in his memory!

Here's the silver 400th meeting anniversary of the Minneapolis Numismatic Society which is nearly 4 oz of silver. I have other metals too but need to dig out the photos It was designed by Gale Vergil Highsmith, the President of the MNS. I never met him but believe I would have liked chatting with him given the design he came up with. Did anyone here know him?

Not an anniversary token, but a club one.
Lance.

One of my favorite Daniel Carr designs ~ 2008 Knights of the Coin Table issue:

Silver Matte finish with mintage of 27...

Silver Proof finish with mintage of 41...

Silver Proof Award Medal 'Full Moon" Reverse with mintage of 10...

I'm going to deeply miss one of my dearest friends. Such good memories of teaching together at the ANA, attending shows together with Mike helping me at the table. The fun in the evenings, him enjoying "mother's milk" as he called it, and I something usually different as I had a different taste in an evening drink. The fun we had with some of the YN's who loved to tease Chief (Mike) as was his nickname from the young guys. But Mike would give back as good as he got.
We laughed together, talked coins and particularly Barbers together, and learned a lot from each other. I'm going to miss you terribly my friend. My prayers and thoughts to all his friends and family.

Happy to finish paying for this so I can call it mine.

I couldn't live without this piece. Yes as common as they get but this one I find extremely beautiful.
Thanks for looking and happy hunting, Joe