Business Insider spoke with Anna P. Jay, a private jeweler, about impractical engagement rings.Cavan Images / Samantha Joy/Getty Images/Cavan Images RFThough the look of an engagement ring is important, it must be designed to last.Private jeweler Anna P. Jay said some of the most popular engagement ring styles are impractical.Engagement rings with ultra-thin bands and rings with U-prong settings aren't durable.If you've ever admired someone's en…