Abstract: Interest in gemstones, which have been used as symbols of beauty, wealth and status since prehistoric times,has increased in recent years and taken an important place in many countries. The Menderes Massif is the mostimportant area where bauxite deposits are observed in Turkey. Gemstone quality diaspore crystals are formed only in these deposits. In this study, the mineralogical, geochemical and gemological features of the diaspore formationson the south-western side of the Menderes Massif (Bafa Lake - Milas) were investigated. In field studies carried outin the study area, diaspore crystals were found in the Pınarcık region, located between Bafa Lake and Milas, withinmetabauxite formations together with chloritoid and muscovite, and in some places were encountered in alteredzones close to the metabauxite limestone contact. As a result of petrographic analyses of the wallrock samples,grano-lepidoblastic textured “muscovite-quartzschist”, “quartz-phyllite”, “mica-quartzschist” and lepidoblastictextured “phyllite”, and nematoblastic textured “greenschist-chlorite-epidote fels” rocks were identified. To evaluatethe main oxide, traces and rare earth elements on the 28 collected samples, Al2O3-SiO2-Fe2O3 triangular variationwas used. According to the classification, the bauxite samples were determined to be in the “ferric bauxite” and“bauxite” areas. As a result of SEM imaging and EDS analyses performed on the samples, it was determined thatthe samples mainly contained O, Al and Si. K, Na, Fe, Ca and Mg were also found close to these elements. UsingRaman Spectroscopy, in the light of matching values obtained from the microscope`s own database, it was seenthat the samples taken from Pınarcık (PI) region were diaspore, and brucite (Mg(OH)2)) and ugillite (Ca3(Ti, Al,Zr)9O20) minerals were also detected. In addition, FTIR analysis was performed on 4 samples taken from Pınarcık(PI) region and according to the results of their analysis, it was seen that the samples were compatible with standardwavelength references. It was scientifically proven that the samples collected from the region and subjected to facetprocessing are gemstone quality diaspore crystals with various color variations. This study will make an importantcontribution to understanding the properties of the gemstone quality diaspore mineral, its formation, and findingsimilar formations in the region.