OK, according to Witcher, who's been looking for MK swirls for 15 years or so and found only about 35 -- most damaged in some way -- there are 5 different color combinations amongst the ones he's been able to gather up:
1. Red, blue, yellow
2. Red, green, yellow
3. Red, green, blue
4. Brown/purple, green, blue
5. Orange, blue, yellow
All on a white base glass, generally mixed with clear, which you can see if you look closely; kinda wispy-like in some places.
Obviously the #5 combination is closest to yours, but yours lacks the yellow, and apparently all of the MK swirls he has and has seen have 3 colors (on white). The white of yours looks OK. But the main thing that would keep me from thinking MK swirl now is the very clear ribbon definition that all of the illustrated ones have.
So . . . maybe not an elusive MK swirl. Or at least the probabilities are better that it's something else. Maybe it will ring a bell with someone more versed in WV swirls than me.
Here's another view to go with the one up there in post #13.