The inserts of a casino chip are markings you see on the side of the chips.
These markings are specific to each casino. In other words, the inserts used for Bellagio casino chips can not be used by another casino in Nevada. They are used to easily identify the casinos chips in a stack. We have a few pictures of different styles and designs of casino chip inserts below.

Las Vegas MGM Grand $5 Casino Chip

2 Gray Inserts

3 Pink & 3 Orange Inserts

Las Vegas Westward Ho Casino Chip

8 Black Inserts

Las Vegas Wild Wild West $25 Casino Chip

4 Pink & 4 Lavender Inserts

Las Vegas Horseshoe Hall of Fame $500 Casino Chip

8 White & 4 Orange Inserts

Las Vegas Thunderbird $100 Casino Chip

6 Maroon & 3 Gray Inserts