Prepared by the Imperial Cushions editorial team. Laboratory terminology is retained where a report is cited; historical context and dealer judgment are identified as interpretation.
Fluorescence describes a diamond’s response to ultraviolet light. Its practical effect varies from stone to stone.
Why antique stones deserve individual review
Older cuts, body colour, transparency and facet architecture can change how fluorescence is perceived. A strong laboratory description does not by itself prove that a stone will appear hazy.
What to request
Review the stone in daylight, mixed indoor light and controlled ultraviolet conditions. Ask whether any milkiness or loss of transparency is visible and compare the observation with the laboratory report.
A balanced conclusion
Fluorescence may be neutral, attractive or undesirable depending on the individual diamond. It should be priced and judged as part of the whole stone, not through a rule applied without inspection.