Magical Corian

About a month ago, I did this to the counter:

We weren't entirely sure what kind of counter we had, and I was almost certain the previous owners said it was Silestone. But it turned out that looking up at the underside of the counter from inside the cupboards revealed a label and we have Corian in "Midnight." That still didn't help us know what to do though yet again the care instructions make it sound invincible (or certainly invincible to an essential oil which, I confirmed, would merely cause mild irritation to the skin at full concentration).

So, for a while, we did nothing. And that may be the best thing to be doing. Just going about our normal business, here is the same spot as of yesterday, in different lighting:

I tried deliberately to choose angles and lighting where the ring was most dramatic, so you can see it has faded significantly. Not a clue why or how. Are we somehow re-adding oils? Orange oil is a known cleaning product so maybe the essential oil just "overly cleaned" the counter and now it is becoming shiny with grease? Regardless, it looks like if we continue to ignore this problem, it will go away on its own. For once, benign neglect seems to be the way to go (now if only that same strategy worked with our yard...).