A casino chip is obsolete if:

1. It is not used for any purpose at the casino and is not available at the casino; and

2. In the case where the casino does not have any, it would not be used for any purpose or available for sale IF the casino had any.

You cannot use redemption as a criteria. Circus Circus Reno has a policy of redeeming any chip they've ever issued. They call that "good business." And tell me that the cage critter at Harrah's wouldn't give me $2.50 cash for my Harrah's sultan snapper. A lot of people know those old chips are worth big money.

Unfortunately, I can't imagine any useful definition for obsolete that does not consider the INTENTION of the casino. And casinos are notorious for not sharing their intentions or vault inventory. Who knows what old chips are sitting in the vault somewhere that could be pressed into play for some reason. The chip below was legitimately considered obsolete for years. Then BAM! They were on the craps table. Not obsolete. Sort of like RARE chips that suddenly aren't rare anymore. It happens.