It looks to me like the entire chip was faded at one time. At some point, the chip came in contact with a hard surface that had some sort of oil, wax, or other light penetrating substance, sort of like a tightly stretched linen cloth on a hard surface containing a small trace of the penetrating substance. If the face of the chip only came in contact with the smooth flat cloth the substance would only penetrate on the high surface of the chip and not get down into the Hat, Cane, or recessed inlay area. That is my opinion. Having fun, safe and sane Steve 😜