1930 S Standing Liberty .it's Beautiful!

It's not AT, I have several old Mercs and SLQ's with identical toning, I call it keepsake box toning or envelope/album toning depending on if it's one sided or both sides.
I once bought an old brown cover coin board type album with Mercs in it, all of which had the same colorful obverse toning present on very worn coins. I still have quite a few of them around.

This much I do know about toning is that the TPG's do not always get it right. I seen so many coins that are known AT get into a straight grade holders, and sometime the NT gets the Detail grade. I am good with the coin being jewelry box toned. Enjoy your colorful example.

The 1929 looks original with colorful toning. Note the protected area around the dress and legs is not toned because on circulated SLQ's under XF that area fill up with crud and will not tone unless the area is cleaned.

On the 1930 S the protected area around the dress is toned, so we know the coin has been cleaned. The progression of colors in the dress area did not look natural as the date starts in blue, the dress area goes to red, orange, yellow and back to blue. Most NT SLQ in the dress area get one or two colors not 4 or 5 colors. The rim area of LIB starts in red and goes to blue, and the rim area of ERTY starts in blue and goes to red that is typical for album toning. Most rim toning starts with the darker color and goes to a lighter color. When I looked at the coin, there were inconsistences for natural toning.

Below is one of my SLQ PCGS AU58 colorful album toned that is common on the SLQ. Note the progression of color of blue, red, yellow.