The 5th C: Fluorescence

PostBy Avi Paz Group At 07.11.2010

My diamond? Fluorescent? It's more likely than you think…

Fluorescence in diamonds is the visible wavelengths that the diamond emits under invisible radiation. Nearly all natural diamonds fluoresce under X-rays, and approximately 1/3 of natural diamonds fluoresce under ultraviolet (UV) light, which "excites" the electrons in the diamond crystal. 

While in rare cases a diamond's fluorescence will appear white, yellow, orange, red, or green, the vast majority of diamond fluorescence is blue, which is significant when discussing how fluorescence affects a diamond's color. 

Since nearly all diamonds contain some slight yellow or brown hue (the Gemological Institute of America's color grading scale accounts for this phenomenon), blue fluorescence can mitigate the yellow color of diamonds in the middle of the spectrum, from J-M, making them appear whiter. Conversely, many in the diamond trade now believe that fluorescence obscures the natural light of a diamond with a higher color grade (D-F), which is why stones that have a high color grade but contain fluorescence are often less valued and therefore less expensive. 

However, this wasn't always the case. At one time fluorescence was prized in D-F grade diamonds and these stones were sold as "blue-white" diamonds. But when salespeople began using the "blue-white" moniker to refer to any fluorescent diamond, use of the term was prohibited by law. 

Fluorescence is one of the many parameters Avi Paz Group assigns to the diamonds in its online inventory. Customers are welcome to log on and refine their search by one of seven levels of fluorescence, from Very Strong to None.