Concealers come in liquid, stick, and pot forms.
If your undereye circles are purple or blue, look for concealers with a hint (or more) of orange or yellow.
Since all women don't share the same color skin tone, spot concealers can be mixed and matched until a suitable shade is achieved.
Spotter Brush - Use with spot concealers.
You may even want to try their concealers, powders and foundations too.