The first thing I do with a white earring is hold it up against the inside of my wrist, because white is never just white. Some are a hard, bright white that reads almost blue under office lighting, and some have gone slightly cream or ivory, which sits much better against most skin and most other jewellery you already own. I learned this the slow way, buying a pair of chalky white hoops years ago that looked lovely in the shop and faintly institutional everywhere else. The finish matters more than the shape.
Once you've got the shade right, white earrings turn out to be oddly easy to live with, which I didn't expect. They sit happily against gold or silver, so you're not locked into matching metals the way you are with coloured stones. They work with navy and black without looking stark, and against cream or oatmeal knitwear they just disappear in the best way, adding a bit of light near the face rather than shouting for attention. I wear a pair of small white button studs with almost everything from a plain white earring is also, usefully, one of the few things that reads as dressed up without actually being dressy, so it moves from a Tuesday at the desk to a Saturday evening without any wardrobe negotiation. Summer is where they properly come into their own, against bare arms and a tan, but I'd argue they're just as good in January, a small bright thing against a grey coat on a grey day, which is not nothing in Norwich in February.
How they hold up depends entirely on what's underneath the white. A lot of the cheaper ones use a coating or a painted finish, and that's the bit to check with a thumbnail before you buy, gently, like you're testing a nectarine. If it scratches off in the shop it will certainly come off after a few weeks in the bottom of a bag with your keys. The better ones use a white material or stone all the way through, shell or a proper enamel rather than paint, and those survive being thrown in a handbag, survive sweat, survive being forgotten in a coat pocket over a damp weekend. I've one pair that's been through two years of exactly that treatment and still looks new, which I consider a small triumph given how little care I've given it.
Would I still like the colour of this one in a changing room with ordinary lighting, not the flattering kind, and does the white look like it goes all the way through, or just over the top?