Blue quartz

Blue quartz was an ornamental stone found in the Realms.

Description
This gem-quality variety of quartz was pale blue and flawlessly transparent. It was rare to find sizeable specimens, but fist-sized and larger gems were known. A typical stone had a base value of 10 gp.

Powers
Large blue quartz crystals were the preferred ingredient to produce a gem of seeing, especially in ancient times. More modern uses include being a material component in casting scrying spells and, when properly sliced, prepared, and enchanted, as lenses for the various magical eyes, such as eyes of charming, eyes of the eagle, and eyes of minute seeing.