WHAT IS FLUORESCENCE IN A DIAMOND?
Fluorescence in a diamond under UV light
Fluorescence is a diamond characteristic that is often misunderstood. The reason? Before you purchase a diamond you may have noticed the term “fluorescence” on the diamond certificate and wondered whether fluorescence in a diamond is a good or bad thing. When we talk about fluorescence, we refer to the phenomenon that causes diamonds to emit a soft blue-coloured glow when exposed to ultraviolet (UV) light. We are exposed to this UV light every day through sunlight and in the light produced by fluorescent light bulbs. Fluorescence is caused by the presence of Nitrogen and is a natural characteristic that affects nearly one-third of all gem grade diamonds.
TWO FACTORS SHOULD BE CONSIDERED WHEN LOOKING AT A DIAMOND’S FLUORESCENCE, NAMELY THE COLOUR AND STRENGTH:
The degree of fluorescence in a diamond, from None to Very Strong as seen under UV light
THE COLOUR OF THE FLUORESCENCE IN A DIAMOND
Did you know the most common colour of fluorescence is blue (95%), followed by yellow? The other colours of fluorescence are known to be extremely rare. When a diamond fluoresces blue it has a tendency to appear whiter in colour than its true body colour; this makes the diamond appear higher in colour quality than it actually is. But, if the diamond fluoresces yellow in an ultraviolet light, the diamond will appear lower in colour, causing a negative impact on the appearance.
THE STRENGTH OF THE FLUORESCENCE IN A DIAMOND
Another aspect to consider is the strength of fluorescence, which varies from none, faint and medium to strong and very strong. GIA studies have shown that, for the overwhelming majority of diamonds, the strength of fluorescence has no widely notable effect on appearance. Some diamonds have extremely strong fluorescence and appear oily or cloudy even in normal lighting conditions, giving the diamond a dull appearance.
BUYING A DIAMOND? QUESTIONS TO ASK ABOUT A DIAMOND’S FLUORESCENCE
Before purchasing a diamond it’s important to know the meaning of fluorescence and what impact it has on the overall appearance of a diamond. Explore every aspect of fluorescence by asking yourself the following questions:
A diamond’s fluorescence is noted on a GIA Grading Report
1. IS FLUORESCENCE A GOOD OR BAD THING TO HAVE IN A DIAMOND?
Fluorescence can have either a positive or a negative impact on the colour and overall look of a colourless diamond when viewed in natural daylight. Colourless diamonds with a high colour grading (D, E or F), exhibiting medium to strong fluorescence, can sometimes appear cloudy or ‘oily’ in direct sunlight. Diamonds with a low colour grading (around I or J), especially those with a yellowish tint, can appear one or two grades better in colour because of the masking effect of blue fluorescence.
2. DOES FLUORESCENCE HAVE AN IMPACT ON THE VALUE OF A DIAMOND?
The effect of fluorescence on the value of a colourless diamond depends on the strength and colour. A strong yellow fluorescence may bring diamond prices down, while a blue fluorescence with a yellowish tone can help increase the price of diamonds.
3. DOES YOUR DIAMOND HAVE FLUORESCENCE?
The best way to confirm without a doubt whether your diamond is fluorescent or not is to view your diamond certificate. Diamonds certified by the GIA will clearly state the presence of fluorescence in the diamond. If fluorescence is marked as ‘none’ on your diamond certificate, then your diamond does not have fluorescence. If fluorescence is present in the diamond, the certificate will state ‘faint’, ‘medium’, ‘strong’ or ‘very strong’.
Although some may prefer a non-fluorescent diamond over a fluorescent diamond, you shouldn’t let it be a major influence on your choice, when selecting a diamond. Diamond fluorescence is a natural phenomenon and its best judged by considering the diamond on its own visual qualities and characteristics. In the end, it’s up to personal preference when it comes to the overall look of a diamond.
For more fascinating facts about diamonds visit the extraordinary Cape Town Diamond Museum at the Clock Tower, Waterfront. Book your personally guided tour today.