Why Do Diamonds Sparkle?
When it comes to gemstones that sparkle, nothing surpasses a diamond. Diamond experts will talk about terms like brilliance, scintillation and fire, but what do they mean and how do they relate to a diamond’s sparkle.
Brilliance is simply how bright the diamond appears in light. In other words, how much light is “returned” from the diamond. A high brilliance diamond will return a large amount of light when viewed from the top. Scintillation is the intense sparkles of white and colored light you see when a diamond moves in a light source. Fire are the flashes and sparkles of colored light seen within a diamond.
A good analogy is to think of a mirror. Shining a bright light on a mirror will cause a lot of brilliance but no scintillation. Now take a hammer and break the mirror into many small pieces, then shine a light on the pieces and you will see scintillation. Depending on the size of the mirror pieces, you will see broad flashes of light or “pin” flashes. Now instead of a mirror break a prism into small pieces. Shine a light on the pieces of prism and you will see “fire”.
A well-cut diamond is a combination of both the mirror and the prism. And that’s where the magic is, in the cut.
Diamond cutters have known for quite some time that diamonds with small tables and steep crown angles will have a more “fiery” appearance. However, this comes at some expense as diamonds with these dimensions will also have less brilliance.
To Complicate matters further, a good diamond cutter can create stones which place an emphasis on broader flashes of scintillation, or they can create stones that put an emphasis on pin flash scintillation, or they can cut a diamond that will be a mixture of both. Historically, older cut diamonds tended to have a broader flash, while more modern cut diamonds emphasize pin flash.
For Princess Cut diamonds, experts have typically recommended a range of cut parameters. Several configurations exist; the main differences are in the construction of the pavilion. As the Princess Cut facets get smaller, broad scintillation diminishes in favor of pin flash scintillation.
In the end, it is a matter of personal taste or preference. You may prefer a diamond which emphasizes brilliance over fire, or you may like a diamond that maximizes scintillation or perhaps a diamond that is a balance of all three.
Below are two YouTube videos that demonstrate scintillation and fire.