Like natural diamonds, laboratory-grown diamonds can fluoresce under ultraviolet (UV) light. This remarkable feature makes the diamonds shine with beautiful colors or a brighter shade of white. Lab-created diamonds can also shine just like mined diamonds, since they contain submicroscopic structures. A lab-created diamond that contains impurities such as nitrogen is likely to glow in the dark.
Diamonds that belong to a group called type IIB tend to appear blue. However, after absorbing high-energy light, such as UV light, type IIB diamonds glow in the dark for a short period of time. This residual glow refers to the phosphorescence of a diamond that varies in color from blue to pink and fiery red, depending on the diamond. Diamonds contain different chemical elements that, depending on their concentration, can glow in the dark.
For example, if you go to a nightclub and it turns out that there is ultraviolet light, your diamond may start to glow blue. This is one of the many reasons why it is imperative that a laboratory diamond expert inspect your diamond before purchasing it. To learn more about these brilliant phosphorescent gems, chemical engineers at the Gemological Institute of America studied the Aurora Heart Collection, which contains 239 colored diamonds and a series of type IIB blue stones, in addition to the Smithsonian's Esperanza diamond and its blue heart diamond. The milky effect seen in strong fluorescence diamond is supposed to be present because the diamonds are not of the best quality.
The world-renowned Hope Diamond, for example, glows a beautiful orange-red until a minute after the lights go out. While most blue diamonds appear to glow blue-green after exposure to ultraviolet rays, the study showed that blue often covers a red phosphorescence and that Hope diamond simply has a stronger red glow than most. Beautiful and rare, natural diamonds are extremely valuable, making them a widespread and obvious target for thieves, and fake diamonds that look real (most of which yes, even to the expert eye) are often sold at a steep price as well. Synthetic diamonds do not fluoresce, so if a stone is fluorescent, it is certainly a real diamond; however, keep in mind that approximately two-thirds of real diamonds do not fluoresce.
The diamond in the center showed weak phosphorescence (acceptable in Ada Diamonds), and the diamond on the right showed strong phosphorescence. If a certain gemstone does not shine in areas with less light, it would be inaccurate to assume that it is fake, since it could fall into the category of naturally extracted diamonds that lack fluorescence. After being exposed to this light, each of the Type IIB natural diamonds shone for several seconds. Because each and every diamond is different, scientists realized that they could use the color of the glow and how quickly the shine fades as a type of fingerprint to identify individual gems. When diamond contains specific chemical impurities, it is likely to shine when subjected to ultraviolet light.