What is the most common crystal habit of blue sapphire?

The most common crystal habit of blue sapphire is spindle-shaped hexagonal pyramid or bipyramid. This crystal habit is characteristic of corundum, which is the mineral species to which sapphires belong. In its natural form, sapphire crystals typically grow in a hexagonal shape, exhibiting both pyramidal and prismatic features. This distinctive spindle shape is conducive to creating the beautiful sharp edges and lustrous surfaces that are prized in gemstones.

The hexagonal symmetry allows for the growth of well-defined crystals that can be recognized and identified by gemologists. Understanding the crystal habit helps in the identification and evaluation of sapphires, aiding in distinguishing them from other similar gemstones. The unique spindle shape is not only visually appealing but also contributes to the physical and optical properties that enhance the sapphire's color and brilliance. This knowledge is foundational in the study of colored stones, providing insight into the mineralogical classification and characteristics of gemstones.