Which property is described as an efficient visual test for diamond identification?

• A. Luminescence
• B. Dispersion
• C. Luster
• D. Brightness

Answer: (A)

Luminescence is the emission of visible light by a material after it’s been excited, for example by ultraviolet radiation. Diamonds often glow when exposed to UV light, typically showing a blue fluorescence, though colors can vary. This makes luminescence a highly efficient visual test because you can quickly check with a small UV lamp in a dark area and get an immediate, non-destructive clue about whether a stone behaves like a diamond under stimulation. Many common simulants don’t produce the same glow or emit it in a different color, so spotting a characteristic fluorescence helps distinguish diamonds from look-alikes at a glance. Keep in mind that not all diamonds fluoresce and fluorescence can vary, so this test supports identification but isn’t definitive on its own.