You might want to start by finding a local jeweler you can trust, that you feel is in sync with your style, ask them to help you. Any experienced jeweler should know the industry pretty well.
My husband and I had our wedding bands designed and crafted by Ringworks -- a husband/wife team that used to be in Madison Park, now is on Vashon Island. I went with a sapphire on my ring--I'm not into diamonds--was impressed, nonetheless, by their knowledge of the diamond industry (history, ethical/environmental issues, etc.) as well as their expertise on other stones.