If you use a slotted royal gem in your helmet slot, your gravity will increase even if you have no gravity altering items or gems equipped. While this is not a huge issue (even with max gem you can still jump up blocks) it is kind of annoying as it makes jumping more frustrating, and I don't want to have to slot in a lunar gem to counteract this effect. A simple solution could be to check if player gravity is the default gravity, and leave it unchanged if it is, and otherwise provide the multiplier.

Royal gem (any %bonus) also gives unlimited feathers when you also have the https://www.curseforge.com/minecraft/mc-mods/feathers Mod also installed.

To recreate add any Royal gem into any slot on any piece of armor what a couple seconds and your feather bar will turn "energized" (meaning it will turn orange and youll have unlimited feather regeneration.)