When a chip is listed as part of a "Series", only one chip in the Series is pictured when you look at the chips in that casino although all the series chips are listed with CG numbers and Catalog numbers. You can see the chip you ask about in the No Cash Value section of Stardust. If you click on Series 5, you see the 25 chip in question. Here's what it looks like.

By the way, does anyone know what the Series 5 chips were used for? Why do they have a $2000 face value chip? This would be useful info to include somewhere in TheChipGuide along with a series of chips (if it's not otherwise obvious).