These are presumably the earrings (http://alt-draco.dreamwidth.org/22380.html) he got for Pansy (http://alt-pansy.dreamwidth.org/43291.html), right?

I wonder if he was planning ahead when he made sure that Narcissa didn't already have a pair like them - in case he and Pansy broke up between the time he ordered them and Valentine's Day, he'd be able to give them to his mum for "Mothering Sunday". It would be quite splendidly Slytherin if he did (even though he was clueless enough not to know how much they'd cost).