Princess Secrets – REVEALED
Photo credit: Alice Alinari on Unsplash

Princess Secrets – REVEALED

The beautiful, playful princess.

Since its introduction by Betezal Amber and Israel Itzkovitz in 1979, the celebrated princess cut has been a favorite among diamond lovers seeking the dynamic sparkle of a round brilliant in a square shape.

Photo credit: idonowidont.com

Jewelers typically like to see a diamond in person before making a purchase decision. This is especially true for princess cuts, because they are renowned for a variety of optical appearances. Under a jewelry store’s spotlights one princess can “sizzle” with electric white scintillation, while a second princess “boils” with big, colorful flashes. Others fall somewhere in-between.

Why the differences?

Diamonds can have wildly different brightness, contrast and scintillation components: When planning and cutting a diamond there are many choices and variables which impact its dynamic visual qualities in different ways. Those variables can cause one princess to “sizzle” and another to “boil” – even when they are a pair of identical carat, color and clarity twins.

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Fire Logic – All Diamonds

When teasing out a diamond’s likely visual character there are some general deductions any experienced jeweler (or diamond lover) can make from the basic measurements. Diamonds with smaller table facets and higher crowns generally disperse light more than diamonds with large tables and flat crowns, so a higher crown often means more visible fire.

Antique Round Example: More Fire

Using the simple round shape, when this single ray of white light enters a diamond with a small table and high crown, it (1) reflects once at bottom left, (2) travels to the right and heads up so that (3) a portion of the ray exits the diamond. Remember that the farther a ray of light travels within diamond material the more it becomes separated into its component spectral (rainbow) colors thanks to diamond’s R.I. The ray travels a long way in this diamond so the separation of white light is exaggerated, as you can see at (3). When this dispersive fan of colors exiting a diamond is wide, the visual result is more perceived rainbow colors, or fire, when that dispersive fan reaches the pupil of a human eye… There is a trade-off for maximizing fire. A notable amount of light is lost inefficiently (4), reducing overall brightness.

Modern Round Example: More Brightness

When a ray of white light enters a diamond with a lower crown it also (1) reflects on the left bottom, (2) travels to the right, then heads up to exit the diamond (3). But it doesn’t travel through nearly as much diamond material. So the degree to which that light ray becomes separated into its spectral rainbow of colors is lessened. The dispersive fan of rainbow colors is thinner and smaller. You actually need to zoom in on the image to see the simulation’s indication that dispersion is, in fact, happening… The amount of light that escapes (4) is reduced in efficiently cut modern rounds, generally making them much brighter than antique cuts.

“Seeing” Fire

When a dispersive-fan of rainbow colors passes across your eye there are two factors which dictate whether or not you perceive that dispersed light as “Fire.”

If the fan arrives to your eye and is large enough that only red enters your pupil – your brain sees a red flash. If green enters – you see a green flash. If blue enters – you see a blue flash (etc). But if the dispersive-fan is physically smaller than the diameter of your eye’s pupil – such that all colors enter simultaneously and recombine – your brain sees a white flash.

Image credit: Crafted by Infinity diamonds

Read more about the physiology of fire in our prior post: Fire and dispersion are not the same thing.

The Mysterious Princess

Princess cuts generally have low crowns. So, in general terms, a well cut princess will display a lot of brightness, and your eyes will detect a modest amount of dispersive fans as fire… And yet two princess cuts with identical table size and crown height can vary in the amount of brightness versus fire they display. Why, you might ask?

Shhh. It’s a secret!

Let’s share, shall we? The bottom of a princess cut, called the pavilion, is fashioned with multiple “chevron” facets in each quadrant. There may be as few as two chevrons, or as many as five chevrons in each quadrant. Sometimes a cutter will even mix the number of chevrons per quadrant – although this is usually because something went awry in the cutting process (stubborn little princess).

This means a princess may have as few as 24 or as many as 48 facets on its pavilion. That’s a huge range.

Let’s get nerdy: Virtual Facets

The number of chevrons becomes more exaggerated by what occurs within the diamond. A diamond’s actual facets create thousands of reflections inside. The reflections which are large enough for our eyes to detect create the brightness and contrast we see. Move the diamond slightly and those patterns shift; light areas become dark and dark areas become light. Move it more and the rapid “on-off” flashes you see are what we call scintillation.

Smaller primary facets mean smaller virtual facets.

Logically, this has an impact on a princess cut’s visual qualities – in two influential manners.

  1. More facets means more scintillation events. A 4 or 5 chevron princess with a greater facet count will break light reflections into smaller, more abundant pieces, creating more abundant, more rapid scintillation.
  2. More facets also mean less visible fire: When the size of the reflective surfaces decreases, so does the size of the dispersive fans exiting the diamond, making it more likely you will perceive that light as a white flash, instead of a component color.

Going back to round diamonds, this is why an old European cut, a modern round brilliant and a Leo diamond – or others with extra facets added – have different visual character, in line with what’s discussed here.

Large dispersive fans seen as fire. Small dispersive fans seen as brightness.

Voilà

If you’re looking for more colored flashes, check out princess cuts with 2-3 chevron configurations on the pavilion. In the most well cut specimens you’ll see spectral colors “boiling” from the stone, especially under multiple bright lights, like a jewelry store setup.

If you’re looking for fast, abundant white scintillation, check out princess cuts with 4-5 chevron configurations on the pavilion. The most well cut stones will display a fast electric “sizzle” with rapid, white flashes. The average cut princess isn’t quite as dynamic – having what many jewelers a “crushed ice” look – but many diamond enthusiasts find the crushed ice appearance appealing.

And now you know some princess secrets.

Photo credit: Kristina Flour on Unsplash
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John Pollard

John Pollard is an educational consultant and subject matter expert for diamond producers, grading laboratories and jewelers in the USA, Europe and Asia. He has lectured for JCK Las Vegas, IGI workshops in New York, Hong Kong, Beijing and Shanghai, the American Gem Society in Washington D.C., GIA's Alumni Association and other industry organizations.

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