Precision

Diamond Cut Precision

As we've stated before, most diamonds look nice under bright lights, but most become noticeably average in normal conditions. Those which continue to sparkle and dance have good cut quality. At Summa Jewelers we separate cut quality into two areas; Cut Performance, which revolves around light return, and Cut Precision which can take top performing diamonds to an even higher level.

Micro Cut Precision, a measure of how well all of a diamond’s facets align with each other in 3D, first became possible in the late 1980s in rounds and is now being utilized in some fancy shapes. It takes improved tools, more time and higher skill sets to accomplish top precision. More importantly it expends more carat weight. When present in top-performing diamonds, cut precision can boost contrast, dispersion, scintillation and overall performance in low-light conditions.

Cut Precision is seen in reflective Optical Symmetry viewers, also known as Hearts & Arrows Viewers. These scopes use a single color and no backlighting to show physical cut alignment. Where other viewers focus only on the crown view, the optical symmetry viewer shows both crown (top) and pavilion (bottom) views.

Note: These are not performance reflectors. They reveal nothing about light return, which is a prerequisite for cut precision to have benefits. Read about the AGS ASET® and Ideal-Scope® in our performance tutorial.

How do Optical Symmetry and Hearts & Arrows Viewers work?

The diamond is set face-down to see pavilion cut precision. It is turned over, face-up, to see crown cut precision. When the viewer is placed over the diamond light from above is coded white and light from the sides is coded red (other colors may be used).

When the diamond is cut so exactly that its facet reflections overlap with each other it produces uniform, kaleidoscopic patterns in the viewer.

Round Brilliant

The Round Brilliant is the only shape with a global nickname for cut precision (“Hearts & Arrows”). The reason for this is obvious when looking through an optical symmetry viewer.

• PAVILION: With the diamond upside-down the overlapping reflections create a pattern of eight symmetrical hearts in the pavilion. It takes six perfectly aligned facets to create a single heart. If any facet is off the entire pattern will be distorted.
• CROWN: Turn the diamond over and you will see eight radiating arrows in the crown. Each arrow is a reflection of two perfectly aligned pavilion mains. The ‘arrows’ are much easier to achieve than the ‘hearts,’ so the hearts view is most important.
  
   

Different Shapes have Different Standards

Fancy cuts are not held to the same standards as Round Brilliants. The crisp uniformity of patterns seen in precisely cut rounds is not possible with more complex facet arrangements. As a result shapes other than round are practically never discussed in terms of cut precision. However, as the benefits of cut precision are studied by research labs and made known to consumers we are confident cut-focused manufacturers will begin to pay attention to their development.
 

Round Brilliant Examples in Optical Symmetry Viewer

Benefits of Cut Precision

Cut Precision fine-tunes diamonds which already enjoy top performance. The better-defined contrast pattern creates sharper on-off scintillation and more primary colors in dispersion (less pastels and earth tones). Precision cutting maximizes the return of all available light, even in softer lighting conditions. This is a logical result of all of the facets, the tiny mirrors inside the diamond, brought into precise alignment with each other.

Why don’t more stores have these viewers?

Because few diamonds remotely approach this level of precision. Since most diamonds look nice under bright lights, these viewers reveal the lack of precision present in the vast majority of the world’s diamonds.

Why aren’t more diamonds cut like this?

A high level of micro-precision takes modern tools and more time to achieve. It also requires the diamond cutter to polish away more carat weight. Assembly-line factories with dated equipment would have to sacrifice more time and produce smaller diamonds to do this, costing millions in time and carat weight. Remember that most consumers are barely aware of how to judge cut quality. As of 2009 only a single digit percentage of the world’s diamonds are even cut for top performance. Far fewer have both top performance and top precision; easily fewer than 1% of all rounds and perhaps 0.01% of princess cuts.

Conclusion

Cut Performance is a result of Cut Precision. Understanding that, diamonds which enjoy high performance and precision are dizzying, dazzling and rare treasures to behold.

The bottom line? CUT is the most important factor to diamond beauty. Nature did her job by giving man an abundance of beautiful rough. At Summa Jewelers we think mother nature’s rough deserves nothing less than the highest possible light performance and the most precise craftsmanship man can achieve.