The Tyemnovo Sveta gemstone, whose name translates roughtly to "Darklight," was a synthetic gem formed from compressed carbon. While it was classified by many as a variety of synthetic diamond, the Darklight was distinguished by its midnight blue fire, which inspired its name. The coloration made the stone unique, as it could only be obtained by the suspension of large quantities of arlescium oxide molecules within the crystalline structure. The presence of so great a percentage of a foreign material presented a significant challenge, as the gem had to be assembled or grown molecule by molecule rather than compressed. It also resulted in a denser stone than conventional diamonds.
The Darklight was used by the Bratstvo Svobodii to represent the Kellemann family, and was most notably used in the insignia of General Aron Kellemann's ring. Darklights were also used as a focusing crystal in one of Kellemann's lightsabers and in his jar'kai staff, producing a midnight blue blade in the former and combining with a sulphur yellow stone to color a pair of blue/yellow mixed blades in the latter. In addition, the stone gave its name to longsword christened Cyertsye Tyemnovo Sveta, or "Heart of the Darklight."