The diamond cut good vs very good is an enormous factor in how well the stone reflects light and sparkles. How a diamond is cut affects its brilliance (how much light it reflects), fire (the way light is broken down into colored flashes) and scintillation (the sparkle when the stone is moved).
A good cut will maximize a diamond’s fire and brilliance. This is because the facets are proportional and balanced, and they present a pattern of light and dark areas that refract and reflect light in tremendous fashion.
Brilliance
Brilliance is the brightness and scintillation that a diamond gives off. This can include flashes of white light and colorful light depending on the way the diamond is cut.
A diamond cuts that has a good amount of brilliance will be able to reflect light back in a crisp, well-balanced manner. This is a big part of what makes a diamond shine, and it’s why you should choose a quality cut.
It’s also important to note that the size of the diamond plays a role in how much fire and brilliance it has. Smaller diamonds tend to be given simplified cuts (fewer facets) because they aren’t able to resolve their dispersive fire, and large diamonds usually have fancy cuts with extra facets.
When looking for a diamond with good fire and brilliance, you’ll want to choose a diamond with a shallow crown angle and large table. This will ensure that the facets reflect light very well and will produce the best overall brilliance and fire.
Fire
Diamond fire, also known as dispersion, is the coloured sparkle you see when you look at a diamond. It’s caused by light being broken down into spectral hues when it enters the stone, then dispersed in various ways throughout its interior.
This varies with the cut of the diamond and the lighting environment, so your eyes may be able to detect more fire in a deep-cut or deeply-faceted diamond. It may be less visible in an overhead light source or in dimly-lit environments, such as a restaurant.
Steep crown angles combined with small tables (like antique diamonds) tend to produce more fire because rays of light travel through more of the diamond’s material, and they disperse more. However, this combination also has less light return.
Scintillation
The flashes of light that appear in diamonds when the gemstone moves in the light are called scintillation. It’s an important part of how a diamond sparkles and it’s a result of light entering a diamond from multiple angles.
A very good diamond cut will have a symmetrical pattern of contrast within the stone that creates a blinking effect across the facets and helps the bright areas look brighter. It also allows light to travel better from the bottom facets to the top, making the diamond livelier and showing off its brilliance.
However, if the diamond has too much contrast it can look too dark or messy and will lack sparkle. A balanced pattern of contrast helps bright areas appear brighter and the darker areas look more dramatic.
Symmetry
A diamond’s symmetry is a measure of how well the different facets line up in relation to each other. Symmetry is also a factor in how a diamond sparkles, as a stone with poor symmetry may bounce light off at odd angles, reducing its brilliance.
Gemologists grade diamonds according to a range of factors, including symmetry and polish. A diamond with excellent symmetry and polish would receive an overall cut grade of Very Good or Excellent.
However, a diamond with very good symmetry but a poor polish could be graded Fair – Good or Poor. This is because diamond cutters sometimes sacrifice symmetry to achieve a better shape, increase weight or remove inclusions.
Conclusion
In this case, the symmetry flaw is compensated for by the loss in material for ideal proportions and a higher price. It’s a sad fact, but sometimes, this is how economics work!
