[2018] Is loot determined when the Seren Spirit spawns, or when you loot it?

Originally posted by CoolBananas69

Previously it was best to wear the Ring of Whispers when doing Gathering skills, but now with the Grace of the Elves, it's also good to wear the Luck of the Dwarves for better loot. So, is it fine to switch rings just before looting or do we have to pick one or the other?