Editorial for Special Issue "Mineralogy and Geochemistry of Gems".

Pegmatites are known to be a source of several (>50) gem-quality minerals [[4]]; and in the present Special Issue, three works related to gems and pegmatites are published [[6]]. Ruby is the red variety and sapphire is the blue variety, while all other coloured corundums are called fancy sapphires and need a colour prefix (e.g., pink sapphire, yellow sapphire). Syngenetic zircon inclusions of magmatic origin were found in these sapphires; however, a few of the measured elements using LA-ICP-MS show that some of these sapphires also fall into the range for "metamorphic" sapphires (e.g., Ga/Mg < 0.8). Voudouris et al. [[36]] offer an overview of collector and gem-quality mineral occurrences from Greece, relating them to various geological environments such as regional metamorphic-metasomatic, alpine-type fissures, plutonic-subvolcanic intrusions and pegmatites, zones of contact metamorphism, and peripheral volcanic rocks. [Extracted from the article]