Knowledge of the durability of a gemstone is critical to understanding the risks involved in the various setting, repair, and cleaning procedures commonly used by the jeweler. Some gemstones need attention in display because of their reaction to heat and/or light. This article reviews gemstone durability considerations for 31 species and their varieties as they affect design decisions as well as repair, cleaning, and display of the piece. In all cases, the reader is advised to consult an experienced bench jeweler before attempting any potentially damaging procedures. The recommendations in this article are offered from a gemological viewpoint and as guidelines only.