Thanks for all the good tips and links. I will enjoy "researching" more tonight.
I don't have a long, lean neck, so will avoid short necklaces. Thanks for the tutorial on necklace-collar placement too.
I'm wearing a sleeveless cowl in cobalt blue today, with a simple semi-precious 1 ct. sunstone (orangey-peachy colored stone) pendant on a slim silver chain that is just visible above the cowl. Its not a low cut cowl (I didn't need a cami under it). After trying on chunkier necklaces, this one seemed best.
Does a long necklace work best if it hangs between or below the chest? Maybe my long necklaces aren't long enough. I'm not busty.
I think I just don't have enough variety to know what is working, so should just go try things on at the store! Sounds like a fun dilemma.