I just received in a couple chips that I wanted to add to my collection on the Chip Guide. According to the Chip Guide, some of the chips should have a UV mark, either a year or a H&C. When I place the chip under a UV light, I can't seem to find markings on either side of the chip. I was wondering, does the UV markings wear off over time or is it permanently in the inlay and should show, if present? Just wondering, most of these chips are in uncirculated condition, so wear shouldn't play a role. Here is a picture of one of the chips in question. The Chip Guide shows all chips of this type having a security date showing the year. I also have a Desert Inn and Excalibur that should also have H&C markings, but I can't find them anywhere. Any help understanding this is appreciated. Thank you!