Djeva's "Fire Blue" cobalt spinel stands out as the most vibrant and deeply colored blue gemstone material available. While cobalt glass shares a similar intensity in color, it falls short in terms of refractive index, dispersion, and durability.<br><br>The flame fusion cobalt spinel is essentially a type of beta-corundum. The process of cultivating a pure spinel crystal through flame fusion may lead to cracking as it cools. However, integrating additional alumina powder (corundum powder with a Mohs hardness of 9) into the mix enhances the crystal's resilience and strength, preventing it from cracking upon cooling. This modification not only fortifies the crystal but also elevates its hardness to a Mohs rating of 8.25, surpassing the typical hardness of standard spinel. <br><br> Cobalt blue spinel presents a fascinating characteristic of red fluorescence. While some specimens exhibit this glowing feature, others do not; however, all of them display vivid red flashes when illuminated under full-spectrum lighting. This phenomenon is truly intriguing!

Djeva 114 "Fire Blue" holds a unique place in gemstone lore, with its production having ceased. Presently, several manufacturers of cobalt flame fusion spinel endeavor to match the luminosity of Djeva's creation, yet none have achieved comparable brilliance. The only other option is spinel grown through the Czochralski method, which comes with a steep price tag. For those seeking a dazzling blue gem that combines beauty with durability to stand the test of time, this material might just be the ideal choice.