Any manufacturer holding a gaming licence in NV needs to place a manufacturers mark somewhere on the chip for every chip they ever produce, regardless of used in NV or not.
That 'mark' can be in the form of the mold used being a proprietary one, or, for example as here, a tiny top hat.
Casinos have the option of that mark being visible, or printed in UV at an EXTRA COST
The top 3 chips are not on proprietary molds so required such marking. In addition to that the GN obviously opted for that extra security watermark of their own.
The UV on the bottom chip would be purely a casino request. The H&C mold is proprietary so didn't need a top hat added.