Polish

Polish is the quality of a diamond's external surface condition as a result of the polishing process. Various features, such as pits or nicks, are considered in evaluating polish. It is graded on a scale ranging from Ideal or Excellent to Poor and is generally listed on a diamond certificate. 

Symmetry

Symmetry is the exactness of a diamond's external shape and the even arrangement of its facets. Therefore, it can be divided into two categories: proportion-related (external) and facet-related (internal). It is also graded on a scale ranging from Ideal or Excellent to Poor and is generally listed on a diamond certificate. 

Proportion

A diamond's proportion is measured by its crown and pavilion angles and the overall measurements of its facets. As facets are like tiny mirrors, their proportion can be a crucial contributor to the overall face-up appearance of a diamond. Proportion can also help professionals understand how well a diamond will produce sparkle.  

Brilliance

Brilliance, sometimes referred to as brightness, is the internal and external white light that reflects from a diamond. Each time light enters a diamond, its internal facets send it off in different directions, depending on the angle and tilt of the facets. Masterfully cut diamonds demonstrate superb brilliance because they bounce light off multiple facet surfaces. 

Fire

Fire is the scattering of white light into the colors of the rainbow. Diamonds are excellent at scattering light and displaying it as a spectrum of colors that glint sparks of red, orange, yellow, green, or blue.  

Diamonds must be precisely cut for light to disperse in this manner. Imprecise, poorer cuts do not refract or scatter light as efficiently; instead, they allow the white light to escape before it can disperse a rainbow of sparkles. 

Scintillation

Scintillation refers to the sparkle a diamond emits as you move it in the light: the facets split the white light into a spectrum of colors, creating sparks of light that appear to dance along the surface of the diamond. This is contrasted sharply against the darker, colored flashes that refract through the inner facets. The symmetry and balance between lighter and darker areas create the overall sparkle.