Jewelers LIE, so you should always make sure that your diamond is legit: Make sure that the diamond has a "cert." This is a written document that lists the clarity, color, cut, and carat of the diamond, so you can know what you're buying. You know the cert is accurate, because it has been independently appraised by the GIA, IGI, EGL, or AGS (these are the only four acceptable appraisal organizations; look for the stamp on the cert). Don't concern yourself with what any of these letters stand for. All that matters is that the diamond must have been looked at by an unbiased pair of eyeballs, and appraised for the 4 Cs (clarity, color, cut and carat).

If the jeweler can't provide a legitimate cert for the diamond, then don't buy it under any circumstances until it has been appraised by an independent expert. For a referral to an independent appraiser in your area, call the International Gemological Institute at (212) 753-7100, and they'll take you through the steps of how to get a diamond appraised.

SoYouWanna know more? Check out our full-length article SYW buy an engagement ring?