Where in London to buy an antique/vintage necklace for a 21st?

[OneDivineHammer]

Preferably white metal, delicate, with a small stone/stones.

I spent hours slogging round Hatton Garden the other day, but all the antique things were too pricy or too bling/Victoriany.
Dd really does not like the 'diamond pendant in a rub-over setting' which seems to constitute much of modern style., and I think she would like more antique/Jugend. I do need to play it a bit safe.

Is there anywhere in London other than Hatton Gdn to find several shops in close proximity, and not too overpriced, please, knowledgeable people?

And I tried Gray's as well - too much on the higher end of prices, sadly (well, all the things I liked, anyway 😂)

Well, if anyone in the future finds this tumbleweed thread, I went to Alfie's Antiques in Marylebone, which was excellent, with lots of great shops and all types of antiques. Thanks MS Co-pilot for the suggestion. 😁

I got a couple of vintage pendants one 1920’s other 1950’s in Camden passage