Tag Archives: wavelengths

Brilliant! What Gives Diamonds their Smashing Sparkle


Diamonds are pretty sparkly, aren’t they?  Ever thought about how that happens?

When a diamond is first found in the dirt, it doesn’t appear that breathtaking.  Yes, it’s hard – the ancient peoples of the world discovered this many moons ago, as they routinely would bludgeon each other with diamond weaponry.  Luckily (for pretty thing enthusiasts), someone got the bright idea to start cutting and polishing these rocks, nice and smooth-like.  That’s when their intrinsic sparkly essence was released for the world to forever wonder over.  Centuries later, diamonds are still hailed as the number one symbol of jewelry elegance, opulence and splendor.  The Cadillac of condensed carbon.  The Clooney of stones.

But what exactly makes them sparkle so?


Much like a heated round of laser tag, it’s all about the light.  Specifically, the speed and direction of light.  “Hmm…isn’t the speed of light a really well known scientific constant?” probably just popped into your head.  Yes, you physics minded smartypants, it is.  However,  hashtag “E=mc2” only applies to light in a vacuum (like that heavy Electrolux your mom used to make you lug around the house).  In the actual world in which we live, light gets slowed down by all the pesky electrons that get in its way.  The denser the material, the more the electrons.  So let’s break it down into some actual figures: light unmolested by electrons flies by at 186,000 miles per second; light passing through water/ice drops down a gear and clocks in at 140,000 mps; light through a pane of window glass hits 120k mps and light trying to mosey through colored/cut/lead-containing glass slows down to 100k mps .  So let’s talk diamonds.  Light basically screeches to a relative halt when trying to pass through a diamond: 80k mps.  That is one turtle-like beam of slow-pokey light.

Now here’s where it gets interesting.

Once light passes from one material to the next, and its speed changes up, something happens to the ray.  Much like a lenient parent acquiescing to an annoying and portly child’s demand for soft-serve with sprinkles, the light bends.  If you happen to catch a beam of sunlight after it hits a glass of water, you may notice how the light curves and then presents itself in what poets and dreamers refer to as a “rainbow.”  However, light is not always this malleable; there is a little trick it has up its sleeve.  It’s called reflection (this is the phenomenon that allowed Narcissus to admire himself and style his hair for hours while looking into a river).  If light hits a flat, colorless substance at an angle, it bounces back – like Mickey Rourke’s career (and equally as brief).


Enter the diamond.  When a shaft of light hits a diamond, penetrating several of the facets, it obviously doesn’t just shoot straight through it, like a BMW speeding past a bad part of town.  The light enters into what is a virtual bouncy castle, pinging and ponging back and forth within the stone before it finally escapes.  But remember the tale of the “Spectacular Sunlight and the Magical Water Glass Spectrum?”  Since ‘white light’ is comprised of ALL the hues of the rainbow, when it penetrates a diamond, something trés cool happens.  The colors traverse in varying ways, meaning each color bends differently within the diamond (this is called refraction: reflection’s limber cousin.)  Now, here’s where the real science-y part comes in: the more distance that the light has to cover, the more the colors break apart from each other – separating into a multitude of wavelengths.  So by the time the light boings around several times within the diamond (bouncing off each reflective surface) and finally emerges, it really becomes dispersed.  Hence the term “dispersion” that gemstone experts use to describe the laser light show that diamonds put on.  All these colors shooting out of the diamond at assorted angles coalesce into that brilliant sparkle, or “fire,” that we lust after.  Other precious gems out there reflect and refract light in dynamic ways as well, but none put on the Fourth of July Fireworks Extravaganza that diamonds do with such spirited ease.


Looking for more fascinating, scintillating and dazzling diamond facts?  Check out Diamond University, our unparalleled forum on diamond expertise.  Looking to sell a diamond?  Check out diamondlighthouse.com.  We don’t buy diamonds, we help you sell yours for the most cash possible.  Find out more here.


-Joe Leone