Do Lab Grown Diamonds Have Fluorescence?

One of the most intriguing things about diamonds is their ability to fluoresce. But do lab grown diamonds have fluorescence?

Many have debated whether fluorescence is really a good or bad characteristic of a diamond. Some love the unique colours fluorescent diamonds produce, while others believe the trait causes a slight haziness in the stone. Diamond fluorescence is considered in diamond grading from major gemstone sources like the Gemological Institute of America (GIA), ranging from “none” (no glow) to “very strong” (intense glowing effect).

Fluorescence occurs when a diamond reacts to UV light sourced from harsh sunlight or black light lamps. Around 30% of diamonds have fluorescence, and most glow blue when exposed to UV light. Others can glow white, green, orange, yellow, blue, red and even purple - though these colours are much rarer than the standard blue. 

If you are considering buying a diamond with fluorescent capabilities, it’s important to first brush up on a few facts. You’ll find plenty of myths surrounding diamond fluorescence, particularly in lab grown diamond jewellery, so it’s good to do your research. Read on for the lowdown.


Do Lab Grown Diamonds Have Fluorescence?

Just like natural diamonds, lab grown diamonds can fluoresce under UltraViolet (UV) light. This remarkable characteristic causes diamonds to glow beautiful colours or a brighter shade of white. Only a small percentage of man-made diamonds have fluorescence, and the glowing effect is usually added during colour-changing irradiation treatment in labs. 

What Causes Fluorescence In Diamonds?

Fluorescence in diamonds is caused by traces of other minerals in the chemical makeup of the stone. These elements are absorbed over time during the diamond formation process deep underground and caught between the layers of carbon that make up a diamond. A select few minerals react to UV light and are the cause of glowing appearance and colour change in the final diamond product. 

These three elements are responsible for fluorescence in diamonds: 

  • Boron 
  • Nitrogen
  • Aluminium

Diamonds change into fancy colours in a similar way. Traces of other elements mixing with the carbon structure of the gemstone will change the overall colour of the diamond. Boron is actually the cause of natural blue diamonds, which is why it’s no surprise you'll see strong blue fluorescence in most glowing diamonds. But what about lab diamonds? It’s a little more complicated. 

What Causes Fluorescence In Lab Grown Diamonds? 

Generally, lab grown diamonds aren’t formed as coloured diamonds or fluorescent diamonds. Scientists aim to create colourless gemstones without any trace of minerals that can turn the diamond’s colour. However, tiny amounts of boron or nitrogen involved in the growing process can cause small fluorescent appearance in the stone before it’s treated or cut.

The most likely cause of fluorescence in man-made diamonds is heat treatment and irradiation processes. Though these processes are usually used to enhance desirable yellow or pink colours, they can also cause the stone to react to UV light like natural diamonds. The process of irradiating a diamond for colour can be complex. Essentially, radiation is passed through a diamond which causes some of the carbon in its structure to move. These small gaps in the lattice cause the diamond to absorb colour differently, and create blue or green colours. Further heat treatment (above 500°C) causes these small breaks in the structure to pair with traces of nitrogen, which in turn creates yellow to pink colours. As we noted before, the presence of nitrogen also causes fluorescence, and intense treatments can create ‘moderate’ to ‘very strong’ glowing effects. 

Both irradiation and heat treatments aren’t generally used to improve fluorescence. Instead, you will find many treated diamonds to be created for intense and beautiful colours. 

Browse our range of lab grown coloured diamonds!

Fluorescence Vs. No Fluorescence Diamond

Fluorescence can have an impact on the way a diamond looks, but not as much as you might think. Of course, under UV light there are major differences between the appearance of diamonds with and without fluorescence. A fluorescent diamond will glow bright colours under UV lamps, while a diamond with no fluorescence won’t show any illumination. Similarly, the UV rays of the harsh sun can make a fluorescent diamond glow or change colour slightly during the day, which is a beautiful sight. 

Where most are unsure is the difference between the two under normal light conditions. Many believe that fluorescence causes a hazy or oily looking appearance in diamonds, lowering the clarity of the stone. This effect is found almost exclusively in stones with very strong fluorescence. 

In a study run by GIA, average jewellery buyers could not consistently identify the difference between stones with some or no fluorescence. Some are able to tell slight differences in the stones, but this isn’t necessarily a bad thing. Fluorescence can actually make some diamonds appear whiter and lighter. Blue fluorescence will counteract any traces of yellow in the precious gemstone, improving its colour. In lower graded diamonds, this effect will increase the overall value of the stone. In very rare cases, a diamond can fluoresce yellow, which will detract from its colour grading. 

Fluorescence has a miniscule effect on the sparkle and clarity of a stone. If you want a diamond with some sparkle, you shouldn’t worry about the effect of fluorescence. Other diamond evaluations are much better indicators of a diamond’s shine. In particular, the cut of a diamond has the most influence over a diamond’s shine. The way a diamond is cut changes how light is reflected through the stone, and is what emphasises the brilliance and beauty of a diamond. In fact, buying a fluorescent diamond may even add to your sparkle — they do have a stunning glow under UV light after all.

Is Faint Fluorescence Okay In A Diamond?

Faint fluorescence in a diamond is almost never a bad thing. The effect is small enough that you won’t notice any haziness or discolouration in the stone, and it may even improve the colour. It would be extremely rare to find any cloudiness in a stone with a ‘faint’ fluorescence evaluation. With a stronger fluorescent effect, an average buyer may be able to discern the difference when compared to a regular diamond. 

For reference, fluorescence is measured in five stages: 

  1. “None” or no fluorescence

  2. Faint fluorescence

  3. Medium fluorescence

  4. Strong fluorescence

  5. Very Strong fluorescence

These labels may make you wonder, does fluorescence affect diamond value? 

Fluorescence evaluations have no effect on the quality rating of a diamond. Well, not in the usual sense. A fluorescence rating is an identifying feature, and not included in the 4Cs of diamond evaluation (colour, cut, clarity, carat). This means a diamond with faint fluorescence is not inherently less or more valuable than one without. 

Where fluorescence can have an impact on the quality rating of a diamond is when it affects one of the 4Cs. As we’ve mentioned, blue fluorescence can actually cause a diamond to have a higher colour grade by reducing any yellow or brown tones. For faint fluorescence, it’s possible for a diamond with an already high colour grade to have a slightly more blue tone. This can be seen as a negative as diamonds are valued for their lack of colour. 

Similarly, the oily or hazy effect sometimes seen in diamonds with “strong” to “very strong” fluorescence can affect the clarity grading. Luckily, when you buy a diamond this information should be readily available. 

Learn more: 

So, Is Diamond Fluorescence Good Or Bad?

That’s up to you. A fluorescent diamond certainly makes a remarkable spectacle, and can make an already beautiful piece that little bit more special. It might be easier to think of fluorescent diamonds like coloured fancy diamonds — you’ll still get that special diamond sparkle plus something even more unique. While the blue glow is most common, you can find diamonds from all over the world that fluoresce incredible colours and are valued like treasure. 

If you aren’t sure, or just love that traditional brilliant diamond look, then take some time to weigh up your options before buying fluorescence. While we might think they’re great in their unique way, it’s best to buy what you are really looking for. Stones with high colour grades will hardly be affected by faint fluorescence, but can be impacted by stronger fluorescent characteristics. 

There’s plenty to think about when buying diamonds. Of course, lab grown vs natural diamonds will continue to be an important choice to make. Lab grown diamonds are less likely to have fluorescence, but have the benefit of being sourced ethically and without damaging important ecosystems. As with any purchase, it’s good to do your research, so feel free to browse our pages to discover why lab grown diamonds are the best choice.

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