1. Have the right tools. Keep a Hanneman filter—or, at the very least, a loupe—on hand to inspect stones.2. Know the telltale signs. Look for flashes of blue and gas bubbles in stones under magnification.3. Keep reliable resources handy. Have a gemologist or laboratory at the ready to help identify the nature of suspect stones.4. Take precautions. Take all stones, including ones in repair jobs and those set in seemingly antique pieces, out of mountings prior to any work, and don’t expose them to chemicals of any kind!5. Get it in writing. Get loose stone and finished jewelry guarantees in writing when buying from vendors.