What is the cut of a diamond?

Diamond-Cut refers to the angle of the diamond facets, the proportion of each part of the diamond after cutting and the smoothness of each face. Its purpose is to allow the diamond to successfully condense and reflect most light. Cut is the most complex and technically demanding of the 4Cs. It has very high requirements regarding accuracy and measurement limits. It also pays attention to the results of polishing, because it directly affects the visual fineness of diamonds.

Although the color and clarity of a diamond are limited by its innate qualities, the exquisite craftsmanship of a diamond’s cut and finish is necessary to reveal a diamond’s total beauty. Among the 4Cs, cut has the greatest influence on scintillation, brightness and fire of a diamond. If not properly cut and polished, even flawless high-color diamonds would look dull.

  

Diamond cut categories

The factors of Cut, Polish and Symmetry work together to determine the ideal light reflection of the diamond.

 

Cut - The scale of each facet or proportion of the diamond. Since the scale of each facet, angles and proportion of every diamond is calculated, it needs a suitable standard size to achieve the best internal reflection and refraction to produce beautiful color beams.

  

Polish - The smoothness of the surface. The smoother the surface, the stronger the surface reflection.

 

Symmetry - The degree to which each facet of a symmetrical or full-grain diamond is cut neatly, such as whether the shape of the circumference is a perfect circle, whether there is a deformed facet, or whether the table is parallel to the bottom.

 

The above three factors have five levels in GIA.

The highest is Excellent (EX), followed by Very Good (VG), Good (G), Fair (F), and the worst is Poor (P)

   

The importance of cut

The cut of a diamond directly affects the angle and direction of light entering our eyes, and thus the degree of sparkle. A high-quality diamond should have a precise ratio and excellent symmetry, so that the light entering the diamond can be internally reflected by different facets and redistributed into a color spectrum, which is finally refracted from the top. Diamonds can shine with dazzling brilliance. If a diamond is cut too deep or too shallow, the light will not be effectively refracted back to the top, but will leak from the side or bottom, reducing the diamond’s brilliance and rendering it relatively dim. This ultimately lowers the value of the stone.

 

   

The cut proportion

The cut proportion of a diamond refers to the relationship between the size and angle of its polished facets. While there is an ideal cut proportion for each diamond, there is no fixed "formula" or proportional value. The ratio is a magical factor that GIA researchers have discovered from more than 70,000 observational tests during the development of the cut grading system. Compared to any single ratio combination, the GIA system places more emphasis on the overall appearance of the diamond. Each cut grade has a certain proportion range, and each diamond at a cut grade will have visual differences, which are reflected in the fire, brightness or pattern. Therefore, a particular diamond may be more attractive to one customer than it is to another, although both customers are equally discerning.

  

Optical effects

The sparkling brilliance of diamonds is the result of optical effects. When light enters the diamond, it effectively gives life to the diamond, directly affecting its visual appeal, especially as the process of moving the diamond is more obvious. The following are terms related to optical effects:

 

Brilliance - Refers to all white light reflections on the outside and inside of the diamond. Diffuse illumination (that is, when the incident light is not from a single direction) is the best measure of brightness. Even if the carat, color and clarity are the same, the brightness of a cut diamond will be greater than a non-cut one. In general, the greater the brightness of a diamond, the higher its cut level.

 

Fire - When white light passes through a diamond, it disperses into a rainbow-like spectral color, creating a fire. In the store's spotlight, you can see a red, orange, yellow or blue beam flickering as you rock the diamond.

 

Scintillation - The result of brilliance and pattern combined. This refers to the spot that flashes when a diamond, person, or light source moves. A high-quality diamond’s light reflection should be uniform and of appropriate size.

 

Pattern - Refers to the relative size, arrangement and external and internal reflection of a diamond, which create a contrast between light and dark areas. The light and dark areas of the diamond must have sufficient contrast to form a clear and degraded pattern, while ensuring dark areas are not overshadowed.

   

What is 'Hearts and Arrows'?

‘Hearts and Arrows’ is a mark that was developed by the Antwerp Diamond Appraisal Agency in 2009 and is regarded as one of the criteria for verifying diamonds. The pattern of the heart and the arrow is a symmetrical optical figure obtained by observing the cutting of a round diamond with a special instrument.

The round brilliant cut diamond has 57 facets. When all the facets reach the symmetrical and specific scale range, the diamond will show a pattern of eight arrows when viewed from above. You will also be able to see eight heart-shaped patterns at the bottom of the diamond. All of these ‘hearts’ and ‘arrows’ are almost exactly the same and nearly perfect.

 

 

Many people misunderstand the ‘Hearts and Arrows’ mark as indicating a perfect cut ratio. It is thought to represent the human heart, with the arrow symbolizing the cutting of the diamond. It draws from the mythical story of Cupid, the god of love, and used to make the diamond a symbol of pure love. Since the cutting method for all Round Brilliant diamonds is standardized, GIA cuts and symmetry ratings of Excellent, Very Good or Good can achieve different levels of the ‘Hearts and Arrows’ effect.