What is Meant by Diamond Fluorescence

If you are interested in the world of diamonds and gemstones in general you may be the sort of person who is curious to learn more and more about what makes diamonds what they are, how they are different and the many unique characteristics they possess. So much so that you wish to learn about what are marginal factors, but in aggregate do count as a distinct quality factor.

Enter the topic of diamond fluorescence. An interesting subject that concerns the emission of visible light from the gemstone! You heard that right, diamonds, like every other gemstone in the natural world, actually emit a light that comes from within. In this Education page, we will break down the subject of fluorescence and fluorescence in diamonds. Why it is important when it comes to determining diamond quality.

What is Fluorescence?

Before we get to diamond fluorescence let’s get a basic grasp of what is meant by the concept of ‘fluorescence’. Which we reckon for some may seem like a new subject that falls outside the conventional debates surrounding diamond quality and value.

The first point about fluorescence is that it is a natural phenomenon. A phenomenon that is found in certain minerals, like diamonds. The question is: how does this happen?

Before we answer this question it is important to note that this is not the place to get into a discussion of the science that underpins this visual effect, but some knowledge of the processes involved in producing it will help when understanding the character of diamond fluorescence. The first point to consider is that fluorescence is primarily about light and its effects, and not colour. At least not primarily.

Colour in the natural world is a function of the interaction between light waves and the materials that absorb the waves that fall in the visual spectrum. For example colour in fancy coloured diamonds is a function of the presence of certain trace minerals which aid the absorption of certain light waves and not others; to produce distinct colours like red, pink, blue and yellow.

With fluorescence however what we encounter is the ability of the gem or whatever mineral in question that has this feature, to give off visible light (i.e. that which glows in the dark) upon contact with a source of radiation, much of it is not visible to the naked eye. A phenomenon of light known as luminescence.

Fluorescence however is a certain kind of luminescence which involves the absorption of radiation, such as ultraviolet rays, to produce glowing photons. The effect is caused by jumps made by the electrons in the mineral, with their movement at an atomic level, producing this lighting effect. It is interesting to note that along with diamonds a considerable number of other minerals (but not the majority) also feature this quality.

What is Fluorescence in Diamonds?

Fluorescence in diamonds takes place due to the presence of certain particles in these carbon-based gemstones, that upon contact with UV (ultraviolet) light produce this glowing effect. That is often blue in colour. Though the effect is relatively light, with varying degrees of intensity.

What causes diamonds to produce this effect is the presence of trace minerals like boron and the manner in which they react to radiation waves. The slight bluish glow that diamonds with this feature showcased under dark conditions is a visible example. However, the level and intensity of fluorescence vary from stone to stone.

An important point to consider is that fluorescence is somewhat widely prevalent in the diamond world. With 15 – 30 per cent of diamonds in the market featuring visible fluorescence. However, the degree to which this effect is visible varies from stone to stone. The visibility of diamond fluorescence is known to have an effect on diamond colour. Since we are talking about colourless or white diamonds, where the presence of any hues or yellowish tones is viewed as a step down in quality.

In diamonds, colour is a quality that is measured on the D – Z scale. Where the quality of the stone goes from no visible colour (D) to high visible colour, usually yellow, in lower colour quality grades (S – Z ). The presence of the fluorescence, with its light blue glow, is generally viewed as a net positive, in diamonds with a lower colour grade (N and lower).

However, this effect is greatly dependent on the nature of the fluorescence that is present in the diamond. As it happens this effect is not uniform in carbon-based gemstones. This takes us to the next main point.

Diamond Fluorescence Classification

Whilst diamonds are technically pure carbon-based gemstones, during the process of development they are subject to numerous effects that alter aspects of the stone. These changes take place at an atomic level, producing changes to the way the diamond (i.e. the mineral) comes to interact with light and radiation.

However, the presence of these trace minerals, notable boron, exists at various levels. In turn, they produce varying levels of fluorescence in the diamonds. In the diamonds and diamond jewellery world, this basically breaks down into the following categories:

• None: Diamonds with no detectable fluorescence.

• Faint: Diamonds with slight fluorescence that is generally visible to the naked eye.

• Medium: Diamonds in this group feature a distinct blue glow which is visible when under UV light. Now diamonds that fall into this range tend to feature a slightly cloudy look.

• Strong: As the name implies diamonds with strong levels of fluorescence emit a discernible blue hue when viewed under UV light. At the same time, some of the negative effects such as a hazy, milky glow are magnified. Which can have an indirect effect on diamond clarity, as it is no longer a colour, but a cloudy look.

• Very Strong: Basically you take everything with respect to fluorescence found in diamonds and you take it to the next level. In diamonds with Very Strong fluorescence, the blue glow that emanates under UV light is significant. And light haze that it produces is clearly visible under the naked eye. On the downside, it will appear cloudy to a point where it will affect diamond clarity.

When it comes to picking a diamond with fluorescence it is best to stick to the Medium to Faint range. These diamonds when combined with diamonds with decent carat and clarity can make an interesting choice. Of course, it is best not to invest in high colour-grade diamonds ( D – H) as some experts in the industry believe that the glowy effects of fluorescence undermine the colour quality of the stone.

Factors to Consider when Purchasing Diamonds with Fluorescence

When it comes to picking a top-quality diamond there is a host of factors to consider. Generally, it is best to start with the 4Cs: colour, clarity, cut and carat and work your way from there. With the addition of fluorescence, you have an added dimension to the mix.

Generally, fluorescence is not a major consideration when it comes to purchasing carbon-based gemstones such as engagement rings. Getting the other diamond quality factors in place takes precedence. Whilst fluorescence is generally viewed as a neutral factor, in high levels (Strong – Very Strong) it becomes a negative and the diamonds which feature them are generally priced lower.

When it comes to buying a gem-quality diamond, fluorescence can be an advantage at lower colour grades. As the blue glow, which is generally viewed positively unlike the yellow tone, can help offset the latter. However, the core qualities of the stone, notably the diamond cut and clarity remain key.