Gems is an events category in JCS, consisting of various gem pickups. Gems can be collected by the player for points. There were plans to award the player and the end of level with an extra live if sufficient gems are collected (100 red gems, 10 blue gems, or 20 green gems), but that code part wasn’t finished – or even started.
This is a subcategory in JCS.
Eat your lima beans, Johnny.