You are in an extremely competitive market with jewellery, and there aren't going to be any easy options unless you can really find a niche, so you have to be realistic with your expectations. Websites are seldom overnight successes, especially new ones in competitive areas.
Adwords is a good option for new websites, especially due to the
google sandbox issue (which downranks new sites in the first several months leaving only less popular more specific long tail searches feasible at first), and due to the sheer competition of your market. Adwords will be expensive too, since you want ads in a competitive marketplace, so looking for niches will help here too.
To get an idea of what people are searching for, use the
google adwords tool, make sure you select "Exact" not "Broad" in the "Match Type" column, but forget about the most popular searches, look for less popular searches which might not be targeted by so many competitors, but are still getting some searches nevertheless.
Then perform those searches on google to see who you are up against. For instance if you are thinking of targeting White Gold Chandelier Earings, do a
phrase search (in quotes) to see how many sites have this phrase, around 7000, then to find out more specifically how many competitors are actively targeting this term, use the intitle:, inurl: or
allintitle:white-gold-chandelier-earings command (google will substitute dashes for spaces), for that particular term there are up to about 480 potential competitors going for the ranking! (and there might be more using other techniques like inurl or inbound links).
Ideally though, SEO is something you really should have considered before setting up the site, as doing the right keyword research would have helped you decided whether or not to go for the online venture in the first place, how to budget for your internet marketing and adwords (so you don't end up spending all your money on the website setup), what to realistically expect and when, what categories and products to focus on, etc.