UNI Data Facets #4. Fluorescence – is it worth investing in?

Let’s talk about Fluorescence in diamonds.

According to GIA, “Fluorescence is the glow you sometimes see when an object emits visible light. Some diamonds fluoresce when they are exposed to ultraviolet (UV) rays from sources like the sun and fluorescent lamps. This can cause them to emit a bluish light or more rarely, a yellow or orangy light. Once the UV light source is removed, the diamond stops fluorescing.”

GIA and WIkipedia both agree that  about one third of all diamonds exhibit fluorescence.  But In reality and based on the strength of the UV frequently used, all Diamonds can fluoresce.  

Generally, diamonds without fluorescence (based on conventional Light measures used by the GIA) command higher prices, while diamonds with strong fluorescence are traded at a lower price. Today, we log in to the UNI Data Platform to research Fluorescence.

First off, let’s check the percentage of fluorescence stones.

Fig. 1 – Number of goods breakdown by Flourescence

Our data shows that 37% of Round stones and 44% of Fancy-shaped diamonds exhibit some forms of fluorescence. The number is somewhat higher than the GIA estimates (25%-35%), but actually very close. So no big surprises here. 

Doing the same breakdown by volume shows similar results:

Fig. 2 – Volume breakdown by Flourescence

So, how does fluorescence really influence the price of a diamond? Let’s find out.

Let’s start with the staple of the market – 1carat Round GIA-certified stones and compare the price of diamonds that have various grades of fluorescence with no-fluorescence stones

We will compare VVS goods, then VS and then SI+I stones.

Fig 3 – Fluorescence discounts for VVS goods, by color

It appears that in VVS1 and VVS2, fluorescence results in over 20% drop in price. We see the deepest discounts in D color, and discounts gradually decrease as we travel to lower colors, but are still significant. 

Fig. 4 – Fluorescence discounts for VS goods, by color

For VS goods, fluorescence discounts are very similar to those for VVS goods, being somewhat lower in most cases.

Looking at lower clarities shows a different picture – in most cases fluorescence results in much smaller discounts than in case of VVS and VS clarities. The difference is especially pronounced on higher colors

Fig. 5 – Fluorescence discounts for SI and I goods, by color

It is well known that for lower colors, some fluorescence may actually improve the diamond color and its beauty. While D, E and F colored diamonds will mostly have a hint of  blueish fluorescence, lower colours can look more exciting in the sunlight and other sources of light. . Therefore, a fluorescent stone with lower colours can look more like colourless or near colourless diamonds and hence be sold in retail almost at the same price as its non-fluorescent counterpart, opening a virtual arbitrage opportunity for traders.

For a more complete picture, let’s also have a look at Fancy shapes.

Fig. 6 – Fluorescence discounts for SI and I goods, by color. Aggregated for all Fancy shapes

We observe much lower fluorescence discounts, especially pronounced in Faint/Slight fluorescence in higher colors. 

As the final part of our research, let’s look into the past and check how fluorescence discounts behaved over time. And the picture we see is quite fascinating:

Fig. 7 – Fluorescent discounts for 1ct Rounds, by color

In D color, the discounts significantly increased over the past 3 months, demonstrating the market’s desire for the purest possible stones. On the other hand, we see that the discounts significantly decreased for E and F colors, and remained largely unchanged for G, H and I. One can say when the market is slower in certain areas, the buyers become more focused on exactly what they want.  But when we get to the mod range level, where the demand was better, the buyer needs to go with what is available.  Supply and demand criteria seem to continue to work effectively in our industry.  

The discussion above demonstrates that there is a complex relationship between price of the diamond and its fluorescence, and while in general no-fluorescence stones command higher prices, the differences are much higher on high colors and clarities for Rounds, while prices of lower colors and Fancies are less affected by fluorescence. We believe fluorescent stones present a great buying opportunity, and we welcome the reader to check out the fine selection on our marketplace.

We would like to end this with a food for thought:  as our retail partners have learned, the consumer does not care about fluorescence as much as the mid market.  In fact we all agree that it actually improves certain diamond values.  So we leave our readers with one question:  If a high flu diamond is truly rare, why not ensure we give it the credit it deserves?  Especially when there may be no physical impact on the natural beauty of the diamond.  Maybe we can work together as an industry and appreciate the beauty of a diamond that is rare and give fluorescence a new outlook for the future.  Rarity and beauty are the cornerstones of all industries working with precious stones.  So, dear reader…. How do we work together to make things better for diamonds and in this case, for fluorescent diamonds? 


Want to get access to our Data Platform or do a custom research? Contact us at data@uni.diamonds

Disclaimer: The information in this report is based on UNI’s data repository that contains actual pricing and availability from over 100 manufacturers and wholesalers around the globe, with combined value of over $1.5B. The information is provided as-is, without any warranties express or implied.