Faceted Zinc Sphalerite, White ZnS Gemstones

These are faceted labmade Zinc Sphalerite (ZnS). While facet-grade sphalerite is only rarely found in nature (and usually has a dark red or orange color), and is very difficult to cut, if you're brave enough to cut it, the resulting stones have incredible fire and dispersion.

Colorless ZnS is grown for use for optics, and various doped versions are used as phosphors - if you have an old oscilloscope, the iconic blue or green display panel likely used ZnS to display.

It also has incredible optical properties, with a high RI of 2.36 and dispersion of 0.16, which make it an amazing gem when faceted. Cut stones are exceptionally beautiful with high brilliance and play of color.  Its major downsides are a hardness of 3.5-4 and perfect cleavage in multiple directions, making Sphalerite firmly a collector's stone.