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The bowtie effect refers to a dark shadow area that looks like a bow tie on the table of fancy cut diamonds. It can be seen on many irregular shaped diamonds, such as oval diamonds, heart diamonds and pear shape diamonds. This bowtie shadow usually stretches across the middle part of the stone, splitting the diamond into two halves visually.
This is basically an optical phenomenon. It happens because light cannot reflect and refract properly inside the diamond. It is not caused by inclusions or impurities inside the diamond itself. The bowtie effect is quite common and matters a lot when you pick fancy shaped diamonds, so you need to pay extra attention to it during selection.
What causes the bowtie effect?
The main reason for the bowtie effect is improper diamond cutting proportions.
First of all, about light leakage. Under ideal conditions, light enters from the top of a diamond. It bounces several times inside the stone and finally refracts back out from the top. This process creates the brilliant sparkle that diamonds are famous for.
Secondly, poor cutting quality will lead to problems. If a diamond is cut too shallow or too deep, or its pavilion angle is not correct, light cannot reflect effectively inside. When light escapes from the sides or the bottom of the diamond, a dark area with no returning light will form right away.
Thirdly, the shape of the diamond also plays a part. Diamonds like oval, pear and marquise have a large length to width ratio. Their elongated shape makes light loss more likely in the center area, which then forms a clear bowtie shadow.
Which diamond shapes are most likely to have the bowtie effect?
The bowtie effect appears most frequently on elongated fancy cut diamonds. The most typical ones are oval cut, pear cut and marquise cut diamonds. It also shows up on radiant cut diamonds quite often.
Sometimes you can also find this shadow on cushion cut and emerald cut diamonds, but the bowtie here is usually not obvious. Thanks to its perfect symmetry, round brilliant cut diamonds almost never have the bowtie effect.
Can we completely avoid the bowtie effect?
Nearly all elongated fancy shaped diamonds have the bowtie effect to some degree, and it is almost impossible to get one with no bowtie at all. So our goal is not to hunt for a totally bowtie-free diamond. Instead, we should choose a stone where the bowtie is faint and not noticeable at all.
How to judge and choose diamonds with the bowtie effect
Seeing the diamond in person is the most important step. Pictures and diamond certificates can not fully show the real look of the bowtie effect. You have to watch real videos or check the physical diamond, and view it from different angles under various lighting conditions.
You also need to tell the severity of the bowtie. A slight bowtie only has a very pale grey shadow. It will not ruin the beauty and sparkle of the diamond, and this kind is totally acceptable.
If the bowtie is obvious, you can see a clear dark grey or black shadow right in the center. It looks like a thick black bowtie across the stone, which greatly damages the appearance and value of the diamond. You should stay away from diamonds like this.
A severe bowtie means there is a huge, deep black area on the diamond. The stone looks flawed and dull. Such diamonds must never be chosen.
It is wise to buy diamonds from reliable sellers. Well-known online jewelry retailers can provide 360-degree high-definition videos of each diamond. These videos let you check the bowtie condition clearly, so remember to watch them carefully before you make a purchase.
Professional cutting also helps a lot. Experienced diamond cutters will adjust the proportions, symmetry and facet angles to reduce the bowtie effect as much as they can. Choosing diamonds with Excellent or Very Good cut grades is a good way to avoid strong bowtie shadows.
When you check a diamond, rotate it and observe from different sides. If the dark shadow stays prominent from most views, you’d better keep looking for other options. Keep searching until you find a nice diamond where the bowtie is barely visible.We can also help you pick diamonds with mild bowtie effect on Blue Nile. Feel free to contact us via the form below.