Fluorescence, properly called photo-luminescence, is caused by a trace amount of the element boron found in the diamond. It is activated by UV light.

Fluorescence in a diamond is described on a certificate (GIA,EGL, etc.) as None, Faint, Medium, Medium blue, Strong, Strong blue and Intense Blue. Other colors of fluorescence do occur, yellow and white for example (try to avoid them), but it is the blue we are most commonly involved with.

In the old days people used to come looking for the perfect "blue-white" diamond. The blue referred to the fluorescence and the white to the diamonds body color.

Around the early nineties, diamonds exhibiting fluorescence went slightly out of fashion. Times change, however, and in recent years GIA have stated that typically fluorescence is a plus in diamonds.

Our suggestion is this. If you are offered a diamond that exhibits fluorescence be sure you examine it under ALL light conditions. That especially includes direct sunlight and a jeweler's black light. Some fluorescent diamonds will actually become hazy in the sunlight and others will glow in a black light environment (including a dance floor) if the fluorescence is Intense (and sometimes Strong). With Strong or Intense fluorescence we advise you to fully examine the stone, as each diamond will exhibit its own traits, and in many cases these traits will have a positive effect.

We seldom sell Strong or Intense blue fluorescent stones, and never one with an adverse effect on the diamond. Faint and Medium fluorescence we have normally found to have, if anything, a positive effect, causing the diamond to have a little "extra life" in the sunlight. If you are dealing with a diamond of H color or lower, fluorescence is normally a plus and will increase the diamonds beauty and desirability.

So to sum up, be sure to examine any diamond with fluorescence under all light forms and make up your mind for yourself as to whether it is a plus or minus.