Simple and classic, a dainty diamond sits in an 18k star pendant on a 14k gold fill chain suspended at 18".
For a more edgy vibe, choose a black star with the same diamond setting, suspended on an 18" rolo chain.
Or, for a totally different style, go with a matte gold bubble chain with or without the star pendant. The matte gold chains layer amazingly with each other or with the black layering necklaces.