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Fluorescence in a diamond is a natural phenomenon that causes 35% of diamonds to glow under ultraviolet light.

A diamond's fluorescence is not visible to the naked eye.

In most diamonds the fluorescence is seen as blue, but in rare cases can be green, yellow or orange.

Fluorescence is caused by the presence of nitrogen in the diamond and does not have any negative effect on the diamond. It also does not affect a diamonds structural integrity in any way.

Many people prefer the appearance of diamonds that have fluorescence in them and also lower grades can come at a lower cost.

Fluorescence in a diamond is another natural characteristic of the diamond. It is measured on the grading report on a scale ranging from None to Very Strong.

The example below shows how diamonds with difference fluorescence levels would look under ultra violet lighting.

Diamonds that we source here at Angelic Diamonds are usually a maximum fluorescence of medium as standard.

If you would like to guarantee any grade please just get in touch and we can certainly look to source a diamond with your exact requirements for you.

The light emitted from diamonds with fluorescence lasts only as long as the diamond is exposed to the ultraviolet source, it will not remain emitting from the diamond once the light has gone, or at any other time.


Fluorescence Grades

No or None

  • No fluorescence will be found in diamonds of this grade, this means no blue glow (or any other colour) will be emitted when the diamond is exposed to UV light.
  • No florescence is normally seen as the most desirable, it is therefore the most expensive grade also.

Faint or Slight

  • Weak fluorescence will be found in diamonds of this grade.
  • A slight blue glow is noticed when the diamond is exposed to UV light.


  • An average amount of fluorescence will be found in Medium Fluorescence diamonds.
  • A light blue glow will be emitted by a diamond, when exposed to UV light.
  • Medium fluorescence offers excellent value for money as diamonds of this grade are for the most part less popular and are therefore cheaper.
  • Medium Fluorescence can actually improve lower Colour grades like that of I, J and K as it can cancel out some of the yellow in these grades.
  • For Medium graded diamonds, the effects of fluorescence are very unlikely to detract from the beauty and sparkle of the stone.

Strong or Very Strong

  • A deep blue glow (Strong) or a very bright blue glow (typically Very Strong) can be seen when these grades are exposed to UV light.
  • Like Medium grade, diamonds with these levels of Fluorescence can improve diamonds with lower Colour grades. They can however, have a slightly negative impact on higher Colour Grades. In a very small amount of diamonds Very Strong Fluorescence can make a diamond look a little gray or in fact hazy but this is the case with less than 0.2% of the fluorescent diamond submitted to GIA.

Diamond Fluorescence is often the most misunderstood diamond characteristic. Diamonds with any fluorescence grade can be used to create absolutely stunning jewellery pieces.

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