Ken:

Me thinks that the circles" within the diamonds are used as either reference points to set up the chip for either molding or hot stamping and that the difference in dept is a result of varations of the amount of pressure on the equipment that they were made on and nothing more.

As for the difference is overprint, I think that this is just an instance of the hot stamping equipment and/or chip picking up some foreign subtance that would prevent the hot stamp from sticking properly. Unless this is a "major" error emcompassing a larger section of the chip, properly not worth nothing.

I do know that people who collect paper money take interest in such stuff as quality control is usualy better and thus, the numer and types of errors/misprint that make it through are a lot less, but given the cost of producing chips and lower qc efforts, a minor error of this is generally not in the same league as say $1.00 stamped on the obverse and $5.00 on the reverse.

Now if you had some of them, that would be something! Espacially if you could get them from the casino for the $1.00 value and then sell them back for the $5.00 value!

John