Get rid of your free plus shipping item and make your announcement bar say free shipping on all items.
Change your add to cart button to a bright color.
If targeting the USA change your jewlrey sizes to inches instead of meters.
Your cart and checkout buttons should be the same bright color. You want it to look uniform.
Get rid of some of the product pictures. You want 4-5 max so it doesnt cover a bunch of the product page
I would spend some time googling other stores and see what their color scheme and product pages look like. You can also hire someone on upwork or fiverr to give you optimization tips and help. https://www.fiverr.com/share/jRA7v