You can spot a good pair of gold plated earrings from across a room, and a bad pair even faster. The good ones catch the light in a warm, buttery way and sit close to the skin like they mean it. The bad ones have a thin, slightly green sheen under certain lights, a clasp that looks like it was an afterthought, and by week three they've started to show a dull pewter patch at the back where your skin has had the final word.
Don't wear them with anything in silver or white gold on the same ear or the same hand, it reads as an accident rather than a choice, and the mix of warm and cool metals close together is one of those things that looks fine until you catch it in a mirror and can't unsee it. They also don't do well against very bright, saturated colour, an orange or a hot pink will fight the warmth of the gold rather than let it sit quietly. The honest limit is that plating is just that, a layer, and it will wear thinner with every swim, every spray of perfume directly onto the neck, every night they're left on in the shower because you couldn't be bothered. If you have sensitive ears, check what the actual post is made of underneath the gold, because plating over a cheap base metal is exactly the combination that leaves your lobes annoyed by Sunday evening. They're brilliant for an office day, for a lunch that might turn into drinks, for anything where you want warmth near your face without the commitment or cost of solid gold, and they're particularly good through fairly dull weather, that light tone does a lot of work when the sky isn't helping you.
In a shop, hold them up to a window rather than under the usual yellow lighting, that's where cheap plating gives itself away. Check the weight in your hand, because a heavy pair will drag at the earlobe by mid afternoon and you'll spend the evening fiddling with them under a table. Press the clasp or the hinge a few times, it should feel like it clicks shut properly and not like it's one firm tug away from the floor. If they're hoops, hold them against your jaw before buying, anything wider than your jawline tends to swing and catch on scarves and hair in a way that gets old fast.
Tomorrow I'd wear mine with a plain fitted jumper in a warm neutral and nothing else on, because gold plating is one of those things that genuinely does better with a bit of space around it.