They (the TV producers or prop-master) used a variety of differently colored chips (some I think with different molds) in the filming. The show was entitled "Lost In Las Vegas" and it is available on the internet for viewing, where you can see (briefly) some of the chips. A way-too-long synopsis of the show can be found here:

https://www.televisionofyore.com/recaps-of-beverly-hills-90210/beverly-hills-90210-season-7-episode-10

Somewhere, it is available for viewing on Youtube, as I've seen the show and the casino scenes. The actors go to several casinos (where they lose all their money - could that actually happen?) and this is why different colors and styles of chips needed to be used. Memory has it that the chips themselves were worn-out "junk" from the Reno area.