Can you use a Potomac Crystal Round in place of a Potomac Crystal Bicone? Or can you use a Potomac Crystal Roundelle instead of a Potomac Crystal Round? In Better Beader Episode 117, Allies addresses the question of "can you substitute crystals?" She helps you become a better beader by showing what to look for in your pattern or a piece you are creating to make the best-educated guess when substituting crystals.