Diamond Fluorescence

By Rachael Fagan

When looking for the perfect diamond ring, everyone will tell you that the most important factors are the 4C’s (cut, colour, clarity and carat) but something that often gets overlooked is a diamonds fluorescence. A lot of the time, people are unclear on the effect that it has on their diamond – is it good or bad? How does it change the colour and price? When buying a diamond, it is important to get as much information as you can to make the best and most informed decision. Following are some of the most common questions asked by our clients that will hopefully help you pick the perfect diamond.

What is diamond fluorescence?

Different chemical elements of a diamond, such as aluminium, boron and nitrogen, can react and this is the reason that a stone can fluoresce. When subjected to ultra violet rays (UV light) from the sun or a fluorescent lamp, these reactions can give off a coloured light. Although most commonly blue, the colour can range from green, yellow, orange and red. Once the diamond has been removed from UV rays, it will stop emitting this coloured light.

Do all diamonds contain fluorescence?

No, there is a limited amount of diamonds that have this trait. Somewhere between 25-35% of all diamonds will have some degree of fluorescence.

How is fluorescence measured?

The Gemological Institute of America (GIA) describe a diamond’s fluorescence by its intensity on the following scale:

  • None
  • Faint
  • Medium
  • Strong
  • Very Strong

In order to accurately grade the fluorescence of a diamond, laboratories use UV spectrum lights and a master set of fluorescent diamonds to compare against. Depending on where the diamond sits on this scale, it’s colour can be effected by the fluorescence. Medium, strong and very strong fluorescence can cause stones lower down the colour scale to appear more colourless in daylight. On the hand, diamonds higher up the colour scale with medium – very strong fluorescence can sometimes look hazy or oily.

Can people tell the difference?

Generally no, to the untrained eye a fluorescent diamond in normal light looks no different to that of one with no fluorescence.

Does it effect the price?

As mentioned above, the effects that strong fluorescence has on a diamonds colour can mean it either looks more colourless or can cause a hazy/oily look within the stone. In these instances yes, fluorescence can result in a diamond costing more or less than its no fluorescence counterparts. However in general, the price is not effected when fluorescence falls to the lower point of the scale.

Is it good or bad?

This is a question that can be answered only by you. Some clients like fluorescence and some do not, a diamond with fluorescence is just as strong and beautiful as one without. There is no right or wrong decision, a diamonds beauty is judged by your love for it.

This website uses cookies to offer you a better browsing experience.