trying to stop players from dropping item.

so as the titles says I'm trying to stop a player from dropping an item because it can break some parts of my mod. so on gem dropped I'm trying to give the player a copy of the item then delete the gem, but I'm unsure how to get rid of the gem without also deleting the item in the inventory. but even if I just want to copy it over to the inventory when dropping it via "q" it works except it doesn't appear until updated. and when dropping it from the inventory it gives the item but still thinks there is something in the previous slot when there isn't I do have it checking for not remote. so I'm unsure of how else to fix this. also is there any way to get when the player moves the item say into a chest so I could stop that.