"Because we've made the change where you can put a gem over another to replace it on an item, we've changed the mechanical function of how a separation drill works as well. No longer will a separation drill degrade or destroy a gem upon removal. Instead, we have made it behave more similarly to that of the normal drills, to add a socket. A separation drill will now be a success chance to simply remove the gem from an item successfully."
Today I had tried to use a separation drill and the gem was lost completely.