When thrifting, it can be challenging to tell crystal from glass just by looking. One of the best methods I've found is the tap test, which lets you listen for the distinctive sound crystal makes compared to glass. Gently tapping the piece with your fingernail or a utensil produces a clear, bell-like ring if it's crystal, whereas glass tends to create a duller tone. Another key sign is how sparkly the crystal is — under the right light, crystal refracts light and shines brilliantly, unlike plain glass. Always examine the cut and weight; crystal tends to be heavier and often has intricate cuts that glass can't replicate as well. When thrifting, handle items carefully and try multiple taps to get familiar with the sounds. Over time, you'll develop an ear for spotting quality crystal pieces which can make your thrift haul truly special. Also, look out for brand marks or labels on the bottom of pieces; well-known crystal manufacturers often mark their products. Combining the tap test with visual inspection and brand recognition drastically increases your chances of scoring authentic crystal at thrift stores, enhancing your collection or home décor.