The Truth Behind BLING: Science or Gimmic

By Fred Cuellar and Diep Doan

What is the #1 requirement we have of a diamond? Hint: see title of article….Very good!! It’s bling–aka sparkle! We expect—heck we demand—that our diamond must sparkle. But let’s stop for a second, and ask ourselves what exactly is sparkle anyway? To answer that question we have to understand light. More precisely we have to understand “visible light”. (See footnote.)

Visible light is our fluid energy, and a diamond is our spectral container. A diamond can take light traveling in excess of 186,000 miles a second and bring it to a crawl at 77,000 miles a second before kicking the sliced and diced light back up into your face. The science of light works together with the diamond to give you sparkle! So what is sparkle? It is white light (brilliance) and colored light (dispersion) that is combined and returned back up to your eye. What a diamond does with light while it is the proud owner will determine how much is spilled/leaked (either out the bottom or sides) and how much will be returned to you, the viewer.

For quite a few years now, diamond cutters have known three things: 1) If the table %, crown angles, girdle thickness, and pavilion angles of a diamond are cut correctly, the interior of the pavilion (the ice cream cone part of the diamond) will respond like mirrors and return light back up to the viewers’ eyes. 2) The diamond cutters also know that depending on the shape and position of the outside facets (the ornaments that decorate the Christmas tree) could create intensity kaleidoscope patterns like hearts and arrows. 3) If you shoot enough light into any diamond of any proportions you could make it look decent as long as it stayed in a well-lit environment.

Where the charlatans took over was when they could take the longest visible wavelength (red), isolate it, increase its magnitude, and give a dead Christmas tree (poorly proportioned diamond) life. First, they put pretty Christmas lights and tinsels on the tree (arrange the facets to create the marketable heart-and-arrow pattern that Madison Avenue could sell to the consumers via Cupid). Others have also tried this lights-and-tinsels trick by creating dozens more facets. As light gets broken up more and more, consumers confuse the difference between more decoration and more sparkle! Do you create more pizza by slicing more pieces on the same pizza? It’s just the same amount of pizza with more SLICES!!! Second, they shoot the dead tree with a bath of red light to influence buyers that it is well-cut because of the presence of a manipulated pattern. Somehow the fact that the appearance of this predetermined pattern can theoretically appear in diamonds regardless of proportions is accidentally omitted in all marketing materials. No one tells you that you can get this with warped diamonds. No one tells you that you can get this with an off-make. Having the presence of this pattern does not ensure your diamond is well-proportioned! Finally, they would turn on a red light, stick it in a heavily lighted box with an instrument sounding name like “Brilliance Scope”, and pretend to measure the sparkle efficiency of the diamond by snapping photographs. Here’s a little question for all who use this equipment as a selling tool. How does this thing work? Apparently, this report is a relative comparison of one diamond to a number of other mystery diamonds. If we have a beauty contest between an ogre, a one-eyed Cyclops, and the wicked witch of the West, the witch may come out on top almost every time! Does this mean that the witch is beautiful? How can we be sure that the mystery diamonds are not ogres or Cyclopes? In the land of the blind, the one eyed man is king.

Principles of physics and mathematics have not changed—only marketing strategies. Let’s go back to the basics. Tolkowsky and Ditchburn proved to us a diamond’s light can be maximized with correct universal crown angles, universal pavilion angles, total depth percentage, table percentage, etc. (See proportions chart on pages 45-47 in 6th edition of “How To Buy A Diamond”.) A diamond with all the correct proportions does not need any special lighting to tell you it sparkles. Under the right conditions, we can all take a good head shot, but we don’t have to take a shot to the head to realize that any diamond that needs an entourage of red lights and lighted boxes are not going to sparkle on a candle-lit dinner and a long walk on the beach under a silvery moon. Stop letting gimmicks mislead you. Let true science guide you to the light!


Visible light hides in a very small region in the electromagnetic field. At one end of the field, we find Gamma rays that travel at wavelengths 10^-6 nanometers (nm) to 10^-2 nm, X-Rays traveling from 10^-2nm to 10nm, and ultraviolet radiation from 10nm to 300nm. On the other side of visible light, we find infrared radiation, microwaves and radio waves. Their wavelengths start at 1nm and extend to 100km. Visible light is a very thin slice of ham squeezed together by two very large pieces of bread. The sun gives us white light (visible light) and a mixture of all the colors. Remember ROYGBIV (red, orange, yellow, green, blue, indigo, and violet)? Each travels at its own wavelength—violet at one end, 400nm, and red (the longest) at 700nm on the other. Indeed, the butcher slices the ham we see very thin!

More questions? Ask the Diamond Guy®

The founder and president of Diamond Cutters International, Fred Cuellar is one of the top diamond experts in the world, as well as a three-time Guinness Book record holder in jewelry design.
Fred Cuellar
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