If you already have retail sales, consider signing up with services like TrustPilot or Feefo. You should also connect your ecommerce site to Google Customer Reviews (via Merchant Center).

This link shows a how-to guide: https://ecommerce-platforms.com/articles/how-to-become-a-google-trusted-store.

Once you collect (hopefully) positive reviews, you can use AdWords Seller Ratings extensions which will add stars and review text into your ads.

As another person suggested, social proof is another important signal of trust. Having a large and engaged social media following is important. If your customer base is so included, Pinterest can be useful (people sharing images wearing your jewelry).

Use a reviews publishing widget to post the best reviews on your site and your other social medias channels.