What is known today about the $500 Agua Caliente chip is what comes from the chip order card. That is the information that is presented on the ChipGuide.

There are probably 1000's of examples of high denomination chips that were in use in casinos that were all destroyed when the casino closed or replaced them with a new rack. I know a collector who takes pictures of high denomination chips while in the casino, before he cashes them in. He then submits them to the ChipGuide. Should these chips not be in the ChipGuide because no one has one in their collection?

As far as uniqueness and value ... the ChipGuide only presents factual information. We can present quantities manufactured, if it is known, but there is no way to know how many currently exist. Value is entirely subjective, only each collector can determine how much a chip is worth to them.