You can't, but you can follow up on it. Remember what Nancy said about the slit she just noticed in the tent?
Leave the tent and turn left to look at the hole from the outside. Hmm ...
Me, I'd rummage around in the sand with my hands, but Nancy is fastidious and demands a tool --
-- so use the shovel (from main room table) on the sand till you find something that tells you where the amulet might have gone. It's going to be in a random spot, but you'll find the shoveling slightly easier if you start from the top left and work right and then down.