A sterling silver necklace is the one that sits against your skin all day and still looks right when you glance in a mirror at five o'clock. It's the chain you put on without thinking, for a desk job, a school run, a wedding you're only half dressed up for. That's its whole purpose, really, something that works without asking you to plan around it.
Where it lets you down is anywhere you want a bit of drama or a lot of shine. Silver is quiet. If you want something that reads from across a room, a chunky gold piece or a bold coloured stone will do that job and silver simply won't, no matter how good the chain is. It's also not the one for daily swimming, hot tubs or heavy cleaning work, the metal will dull and tarnish faster than the label implies, and I learned that the hard way after wearing one in a chlorine pool for a whole summer because I couldn't be bothered to take it off.
It clashes most obviously with rose gold or yellow gold worn in the same spot, you end up with a muddled mess at the collarbone that looks like you got dressed in the dark. Mixed metal can work if it's deliberate and minimal, but two necklaces fighting for the same bit of neck in different metals usually just looks like an accident. It also doesn't do much for very warm, golden skin tones, where it can sit a bit flat and grey against the skin rather than glowing.
Where it earns its spot is everywhere plain and pale. White shirts, grey knitwear, denim, a plain black dress, anything with cool undertones or no real colour statement of its own. It layers well with other silver pieces of different lengths, and it sits nicely under a crew neck or scoop top where only the pendant shows. Pair it with small studs rather than big earrings if you're wearing more than one chain, otherwise your whole top half gets busy.
In the shop, do the obvious checks before you hand over money. Look for a hallmark or stamp confirming it's genuine sterling, not just silver coloured. Run the chain through your fingers, it should feel smooth with no snags or weak links, and the clasp should open and close properly without you wrestling with it one handed in a changing room, which is a specific kind of frustration I don't recommend to anyone. Check the weight, too light and it'll kink and tangle constantly.
It will tarnish eventually, every sterling piece does, and no amount of good buying stops that part.