I came in her with my friend looking for a gemstone engagement ring for her. The salesperson offered no further assistance after stating that only diamonds are suitable for engagement rings because other gemstones are too soft and will have to be replaced "regularly." Obviously diamonds are the most durable stones, but if sapphires are good enough for Kate Middleton, they're certainly good enough for the commoners. We know commissions are highest on diamond sales, but perhaps work with your customers' requests and you might get some commission instead of none.