Hi Pam.
I considered that ... that maybe it was due to fading on one side.
But when you examine the chip closely, you can see that only the surface of the blue side is blue, and that none of the edge is blue except for a couple of spots where the color ran onto the edge a little. And the hot-stamp is so strong on the off-white side that it just doesn't seem to be due to any kind of fading.
So, ... the mystery continues.