When I shop for vintage clothes on Etsy, I looove seeing the store organized by colors.
But if it isn't a clothing shop, I gotta say a variety is way better. If you have a mismosh of items that all together represent your shop, there's a better chance for that one thing that'll catch my eye to stand out to me- which means I'll click to the next page to find more of it.
I don't know where jewelry shops fit into that mix though, I don't ever shop for it so I've got no advice there.