What is Diamond Brilliance?

You may have heard of the term diamond brilliance before. But did you really know what that term meant? Is it just clever marketing, or does it mean something more?

Diamond brilliance is the white light reflected off of a diamond. The brilliance is an optical property of a diamond. It is the basis for a diamond’s sparkle and brightness.

We’ll get into the science of diamond brilliance to explain this property. What is the difference between diamond fire and brilliance? How does it affect a diamond’s sparkle and beauty?

The science of diamond brilliance.

Did you know diamonds don’t naturally brightly sparkle? The sparkle of a diamond is due to its cut. By cutting a diamond at just the right angle, light entering the diamond is reflected back into your eyes.

This reflection of white light is diamond brilliance.

A perfectly cut diamond is cut so that light entering the diamond is reflected back out to the viewer. This is due to the angle of the cut. However, only a small amount of light reflects back. The rest passes through the diamond.

A diamond that is cut at too shallow of an angle won’t reflect much light. This is because light will be reflected out the bottom of the diamond. As a viewer, the light would not be reflected back in your direction.

If the diamond is cut at an angle that is too deep, light will be reflected out the side of the diamond. It won’t have nearly the same sparkle as a properly cut diamond.

 figure below illustrates the paths of light in differently cut round diamonds
Image from http://www.zoominternet.net/~grudolph/diacut.html

You can learn more about the reflection inside a diamond from ScienceABC’s webpage: https://www.scienceabc.com/pure-sciences/why-do-diamonds-sparkle.html

What is the difference between diamond brilliance and diamond fire?

Diamond fire and diamond brilliance contribute to a diamond’s sparkle. Both are considered beautiful. You may have even used these terms interchangeably. However, they are quite different properties.

Diamond brilliance creates the white sparkle of a diamond. It makes it seem like light is pouring out of the diamond. Diamond fire causes the rainbow colored sparkle some diamonds may have.

The reflection of white light inside a diamond is diamond brilliance. Diamond fire is the diffraction of white light into a rainbow of colors. It’s similar to how a rainbow is formed after a rainstorm.

Now for the science. When white light enters a diamond, the speed of that light slows down. Some colors slow down more than others. This is because of their different wavelengths. These different speeds cause the light to separate into a rainbow of colors.

Similar to diamond brilliance, the angle, and cut of the diamond matter. It impacts how much of this colored light is returned to the viewer.

Determining diamond brilliance.

A diamond’s cut can make or break its brilliance. But the angle its cut at isn’t the only thing that affects diamond brilliance. Another aspect is its scintillation.

Scintillation means that some facets (or faces) of the diamond will be dark. Other facets will be reflecting light. This gives a balance and contrast to the diamond.

According to With Clarity, scintillation needs motion. [https://www.withclarity.com/education/diamond-education/diamond-cut/diamond-brilliance]. Either you as the viewer or the diamond needs to be moving in order to see it.

That means diamond brilliance isn’t just about how much light reflection there is. It is where light reflection happens is that also matters.

This contrast between light and dark regions makes the sparkle of a diamond stand out.

What is the ideal diamond brilliance?

The ideal diamond brilliance is a personal preference. A diamond that has less facets will have less brilliance. This is because there are less angles for the diamond to reflect from.

Less facets increase the fire of a diamond. It also shows off a diamond’s clarity more.

A diamond with many facets on its upper surface will have greater brilliance. The trade-off between brilliance and fire is up to you and your preferences.

To get the greatest brilliance, look for “Triple Excellent” diamonds. They are also sometimes called Triple X diamonds. These diamonds have great cut, polish, and finish. They are known for the beloved sparkle that comes with brilliance.

Diamond Brilliance.

Diamond brilliance is a property of diamonds. It is caused by light reflecting off the inside of the diamond back out to the viewer. The cut of a diamond determines its brilliance.

Diamond brilliance makes it seem like light is pouring out of the diamond. It is also the reason why diamonds have their signature sparkle.

Diamond brilliance and fire both create sparkle, but they are quite different. However, there is often a trade-off between the two. It is up to you to decide what balance looks most beautiful to you.

Carl A. Jones, GIA GG

Carl A. Jones is a GIA Graduate Gemologist with over 20 years of experience in the diamond industry. He is an independent jewelry appraiser. He specializes in determining the value of diamonds and advising consumers on how to buy quality diamond jewelry.

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