Ideally, a diamond should reflect every ray of light that enters through its table back through the table. Not every stone is perfect and when we speak of diamonds with a poor make, we usually think of light leakage through the side of the stone or the bottom of the stone.
However, in the case of some fancy cut diamonds, like the oval, marquise or pear, another type of cut imperfection can appear. It is called the bow tie effect whereby a dark shadow can be seen across the width of the diamond in the table facet.
The bow tie effect is in direct relationship with one of the most important characteristics of any diamond, i.e., cut. When there are facets in a diamond that do not reflect light properly no matter what direction you hold them in, this phenomenon can develop.
Contrary to other types of cut problems, the bow tie effect is not caused by the sole issue of light leakage. Instead, it is due to issues in light obstruction caused by the process of viewing the stone itself. I know it may sound strange. How can the process of viewing the diamond be responsible for the bowtie? When an observer looks at a diamond, light rays travelling to the stone are shielded by the human head. This creates the dark shadows that are reflected within the stone.
The bow tie effect looks like what its name implies: two triangles against each other, resembling a man’s typical bow tie.
While it is possible to eliminate or lessen the effect of the bow tie, it isn’t as straightforward as you would think it is. The skill and experience of the cutter plays a large role in this aspect. Whenever cutters are working with the affected shapes (pears, ovals, marquises and hearts), they are also faced with considerations for profitability. The number 1 thing that always matter is to create a beautiful stone without losing too much weight from the rough.
A cutter cannot just say “I am going to cut here or there, because I do not want a bow tie in this stone”. The process is a lot more delicate than as it is determined by a whole range of angles. In order to minimize the bow tie effect in diamonds, one has to carefully design the stone and build a whole new conception by taking into account each angle that might yield unwanted results.
Bowties can give fancy shaped diamonds a sexy appeal and character when it shows up faintly or in moderation. What you would want to avoid are those that are so prominent that they black out a huge area of the diamond.
Many times, jewelers will give an excuse that such dark bowties are inevitable or that these stones are indeed appealing to the eyes. Ignore such claims as these are weak explanations in an attempt to offload poorly cut diamonds onto unsuspecting consumers.
Coming up next, we’ll steer you the right approach to selecting diamonds with faint or small bowties…