Where to get a nice, affordable, gold necklace?

[Donostia]

I have a big birthday coming up, and have asked for & been offered a gold necklace. I have a beautiful heirloom one but I want one I can wear in the bath/to bed and not worry about so much, so not a really precious one. It has to be proper gold and not plated/vermeil (yellow or rose).

I don't know where to look - I've tried Tiffanys but ££££! Everything I'm shown by my generous relative looks miniature Pat Butcher.

Have you seen anywhere (online) that sells simple but sturdy gold necklaces?