How Hearts and Arrows Diamonds are formed
By Bryan Boyne (g.g.) , Tuesday, September 20, 2016
Hearts & Arrows Formation
In April 2004 Whiteflash presented its grading system for Hearts and Arrows optical symmetry at the First International Diamond Cut Conference in Moscow, Russia. It was hoped that laboratories and peers would unite to maintain higher standards for manufacture of diamond sold as "Hearts & Arrows." Though most laboratories do not offer a grade for Hearts & Arrows, Whiteflash does, thereby safeguarding buyers of the A CUT ABOVE® brand with a guarantee of optical symmetry meeting the IDCC presentation criteria. Here is the Whiteflash presentation on the Formation of Hearts and Arrows.
How the Hearts are Formed
Below are views of Hearts & Arrows being forming during the cutting process as they would be seen through a regular Hearts & Arrows Viewer. The leftmost photos show the diamond blocked in 8. The center pair shows the pavilion fully cut, with crown still in 8. The pair on the right show the fully formed Hearts & Arrows when pavilion and crown have both been finished.
The graphic below shows, in sequence, how the main pavilion angles reflect to create the heart pattern. One pavilion facet creates two opposite sides of a heart. Two Pavilion facets create 1 heart and 2 single sides of the next heart and so on until all the hearts are complete. Understand that these reflections must overlap precisely for 8 hearts to appear.
Why H&A better?
Outside the Viewer
This picture shows the main pavilion facets outlined and one heart highlighted in red.
The main pavilion facet reflects on the opposite side, and the lower girdle half separates the arrowhead above the heart.
The Role of the Star Facets
Star facets square off the ends of the heart.
1: Without Star facet in place and
2: With the Star facet in place. Note the squared off heart shape.
The Role of the Upper Girdle Facets
The upper girdle facets complete the patterning around the circumference of the pavilion.
3: Without upper girdle facets and
4: With upper girdle facets in place.
As you can see, it takes a total of 5 different facets working in harmony to create a single Heart with an arrowhead at the tip.
1 Heart = 2 main pavilion facets + 2 lower girdle facets + 1 star facet from the crown
How the Arrows are Formed
In addition to being the foundation of good hearts patterning, the eight main pavilion facets also cause the Arrow effect. These main pavilion facets are the bottom-most facets on the diamond and draw their light from the highest angles. They are the engines which drive light return.
If you have ever wondered what causes these bottom-most facets to appear dark in diamond photos, click here for an article on this phenomenon, known as obstruction.
The shaft of an arrow is formed when one main pavilion facet reflects on the opposite main pavilion facet. The main crown facet allows a different reflective view of the reflected main pavilion facet, thereby forming the arrowhead.
Part One Summary: It's All In The Hearts
If the physical symmetry is not precise the optical symmetry will be affected. In forming the arrows it is easier to camouflage errors since there are fewer facets to align. But it is impossible to hide any inconsistencies in the heart pattern because so many more facet reflections must overlap precisely to complete each heart shape. Even the most minor inconsistencies will make the hearts pattern skewed or distorted. Any lack of optical symmetry will be seen very clearly when viewing the diamond through a Hearts & Arrows Viewer, particularly the pavilion view. This is why we say "it's all in the hearts."
It takes modern tooling, skill and extra time to produce a diamond with true hearts & arrows. Unfortunately, we see many diamonds sold as 'hearts & arrows' which do not hold to the original standards of the Japanese factories where such cuts were first produced. The strategy for acquiring a precise, true pattern must begin with the pavilion patterning. "It's all in the hearts."
Additionally, hearts & arrows diamonds must be cut for maximum performance. Those with crown and pavilion angles close to Tolkowsky's have become known in the trade as 'Superideals.' We strongly feel that any diamond worthy of being called 'Superideal' must have premium light return and light performance as fundamental prerequisites, in addition to true hearts & arrows patterning.
We hope this system is useful to our peers involved in the art of premium diamond cutting. We strongly encourage manufacturers and sellers around the world to unite and set higher global standards for goods represented to consumers as hearts & arrows diamonds.
Learn more in our series on Hearts and Arrows Diamonds:
Hearts and Arrows Formation (This article)
For more specific questions ask our experts