If you're trying to conceal dark purple under eyes you need to use a yellow concealer. If they have more of a blue color use a salmon colored concealer. You can use those under your foundation and then after your foundation use a shade lighter to highlight under eyes.
Are u talking about concelear or color corrected because for concelear I would do one of the light ones and if it's for color correcting then I would use a great or if they aren't two bad I would use a lavender
A light orange color. Always take into consideration that orange/red covers dark circles and if you have a dark skin tone you need more of a red toned and if you have a light skin tone, you need an orange toned or salmon color.