Let’s talk about one of the most interesting topics in gemology. Fluorescence is personally one of my favorite subjects in fancy colored stones. It is a feature that can add uniqueness, influence apparent beauty and also plays a role in determining the price tag of a diamond.

diamonds with various levels of blue fluorescence

So, What is Diamond Fluorescence?

If you have ever attended an introductory physics or chemistry course, you would have probably seen a crystal lattice of diamond where each carbon atom is covalently bonded to 4 other atoms. Under natural formation circumstances, scientifically clear and pure diamonds do not exist as there are always be foreign trace elements or compounds present.

The amount of these compound elements usually defines the quality of the diamond in question. In most cases, the less of them, the better. However, in some special cases the presence of compound elements can result in preferable results. Depending on the type and amount of non-carbonic elements, they can cause coloration (that gives us fancy colored stones!) or give the diamond other special properties.

For example, the presence of different forms of nitrogen, boron and/or aluminum can give the diamond intrinsic properties that might not be seen under regular lightings. While these elements might not directly affect the main color of the stone, they might change the color of light exiting it. Typically, this phenomenon is only visible when electrons of these elements get excited, absorb and release photons under ultraviolet light. This is also known as fluorescence.

Fun fact: the color of the diamond does not necessarily match the color of the glow.

How Does Fluorescence in Fancy Colored Diamonds Manifest Itself?

Fluorescence can be observed in the case of colorless diamonds as well. However, in the case of these gemstones, they usually take on a yellowish or bluish tint due to the nature of its chemical composition. Here’s where things really get wild and interesting.

In fancy colored diamonds, the presence of compound elements is more definite and light has to pass through a colored substance. As a result, fancy colored diamonds typically have a much broader scale of colors when it comes to fluorescence. It is possible to find stones with fluorescence in shades of pink, green, orange, yellow, blue and even white.

Coming up, I will show you some examples of diamonds with different colors of fluorescence under UV lighting conditions.

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