Natural Colour-Change Fluorite
The Black Hole
Fluorite is calcium fluoride, a soft and perfectly cleavable mineral that rewards the cutter with unusually pure colour when the rough survives. A small fraction of material shows a genuine colour change between daylight and incandescent light, driven by rare-earth trace elements rather than by treatment.
The Black Hole is a 1391.46 ct cushion, cut in a combined brilliant and step pattern, and documented in an independent laboratory report as natural colour-change fluorite with no detected treatments: blue in daylight, purple under tungsten.
Rarity Score: 9.7 / 10
Location: Stockholm · Private collection · JDBG GEMS
The colour change
Documented blue in daylight and purple under tungsten by an independent laboratory; the shift is a property of the material's rare-earth trace chemistry, not of any treatment.
A matter of scale
At 1391.46 ct and 65 mm across, the stone is far beyond the size at which clean colour-change fluorite is normally faceted.
Fragility
At Mohs 4 with perfect octahedral cleavage, fluorite is among the most delicate faceted gems. Handled with gloves, never ultrasonically cleaned.
Documentation
Verification is in progress. Photographic record under both light sources, plus acquisition history, held on file for serious enquirers.