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Oval Diamond Bow Tie — What To Look For and Why It’s Bad

An oval diamond bow tie is a pair of black triangles across the middle of the diamond. How can you make sure your oval doesn’t have this hallmark of poor cut?

Before we get into the nitty gritty about what causes an oval diamond bow tie, let’s take a moment to celebrate the oval. Oval diamonds are having a moment. They’re gaining popularity faster than any other cut, and in 2019, they’re one of the most popular choices for engagement rings — and for good reason. The elongated shape is a refreshing change from the conventional round brilliant. Ovals visually lengthen the finger, and add a little extra elegance to a classic solitaire. Ovals also look larger than round diamonds of the same carat, due to their spreading, shallower shape. Even better, they’re slightly lower in cost per carat than rounds, meaning you can get a bit more carat as well. With so much to love, it’s no wonder they’ve gotten so popular.

Unfortunately, selecting an oval diamond is trickier than a round brilliant diamond. This is because of what’s known as the “oval diamond bow tie” effect. But, if you don’t mind putting in extra time, patience, and legwork, the oval cut could be the best choice for you. There are many ways to pick the wrong oval, but the most common. surefire way to mess up an oval is the bow tie effect. So what is it? Why is the oval diamond bow tie bad? How can you be 100% certain that your oval doesn’t have one? Do all ovals have them?

A bow tie

WHAT IS AN OVAL DIAMOND BOW TIE?

A bow tie is a dark area which runs across the diamond and looks like, you guessed it, a bow tie. Ovals, pears, and marquise diamonds all possess this to some extent. A large, dark bow tie is undesirable because it darkens the overall look of your diamond. It’s not the only sign of quality in ovals, but it’s often the most obvious one. Bow ties an be hard to pin down. They look differently in different lights, in different rooms, at different angles, mounted and unmounted. Sometimes you see them, then you don’t.

An oval diamond with a bow tie vs. an oval diamond without a bow tie.

WHAT CAUSES THE OVAL DIAMOND BOW TIE?

When round diamonds are poorly cut, they leak light. That means they have less sparkle, because their facets aren’t bouncing light back out the way it came in. With ovals, the bow tie is light blockage. It means there’s a big shadow that’s being reflected back at you. Do you know what’s blocking the light? Your head. That’s right. Due to the angle of the facets and the way they reflect light, your body and head are preventing the light from ever entering the oval diamond, which leads to the bow tie effect. So, if you want to break up with your oval, you can honestly say “it’s not you, it’s me.”

CAN THE OVAL DIAMOND BOW TIE BE ELIMINATED?

Yes and no. Eliminating a bow tie in an oval diamond isn’t straightforward, and comes with tradeoffs. If it were easy and inexpensive, all ovals would be cut to the same ideal standard and grading accordingly. The reality is each oval is cut to get as much carat as possible out of the piece of rough diamond it’s cut from. Contrary to popular belief, the GIA doesn’t have any standards for what determines a good, very good, ideal, or in this case, bow-tie-less cut. 

Diamond cutters are always experimenting with ways to reduce the bow tie. Cutting an oval diamond wider, or deeper can lessen the presence of bow tie, but it means sacrificing your perfect ratio, or purchasing a diamond that faces up smaller than it should.

DO ALL OVAL DIAMONDS HAVE A BOW TIE?

Bow ties are very common. All ovals have a bow tie effect to some extent. And a little bit of bow tie can actually make a diamond look better. Wait, what? Brace yourself, this is where it gets tricky. Contrast in a diamond is good. Deep darks and bright whites make a diamond beautiful, and dynamic looking. A diamond without any dark areas looks dull. But a little contrast goes a long way, and what you don’t want is a thick black line running across the center of your diamond like someone took a sharpie to it. Contrast = good, a black bar or line = bad.

IS THE BOW TIE LISTED ON THE GRADING REPORT?

If only it were so easy. The presence of a bow tie is not listed on a grading report. There is simply too much personal judgement involved in determining how much bow tie is acceptable. In fact, no fancy cut diamonds are assigned a cut grade by the GIA. That’s because the shapes are more complex and widely varied. There’s more personal preference involved in determining what shape is more or less attractive, and the quality of cut is less objective. For example, the number of facets an oval has is not standardized, some have more and some have less. Unfortunately, all of this extra complexity means that purchasing an oval sight unseen is the easiest way to end up with a big fat bow tie and a lackluster stone.

SO HOW DO YOU BUY AN OVAL DIAMOND WITHOUT A BOWTIE?

The best way is to look at a lot of ovals, until you develop an eye for it. But, that takes time, patience, and a lot of diamonds. So, if you don’t trust your eyes, or are looking for a short cut, here are a couple of tips and tricks you can use to narrow down your choices.

Look at the faceting pattern.

Oval diamonds have four main faceting patterns. They’re called “4 main” “six main” and “eight main” and there are two versions of “eight main” just because. If you look at an oval diamond face up, you’ll notice a star-shaped pattern. The number of “mains” refers to the number of points on that star. While the faceting pattern doesn’t solely determine bow tie, the bow tie is generally less noticeable with more pavillion facets.  

A diagram depicting the different oval cut faceting patterns. Wider ovals are less prone to having the oval diamond bow tie effect.

Use the ASET test to verify the absence of a bow tie in your oval.

If you don’t trust your own eyes to evaluate an oval diamonds bow tie, you can use the ASET. The ASET (Angular Spectrum Evaluation Tool) evaluates a diamonds light performance using an easy to understand color-coded system.  Different colors — red green blue white and black represent different light angles. These colors can quickly and efficiently tell you if your diamonds bow tie is as bad or better then you think it is.

ASET images can be used to determine if your oval is plagued bu the oval diamond bow tie effect. This image shows how to read an ASET.

HOW TO READ AN ASET

Reading an ASET is simple. 

The color red represents the brightest light you’ll see reflected — the more red, the brighter your diamond.

Green represents less bright light coming from lower down.

Blue signifies obstruction. The obstruction is light the diamond couldn’t take in due to your body and head. Sound familiar? In oval, this blue in an ASET shows the diamond’s bow tie.

When looking at an ASET for an oval diamond, you want to see crisp, bright reds intermixed with greens and minimal or fractured blue running across the middle. You don’t want to see a solid line of blue or two large blue triangles.

While most jewelers don’t have ASET images of their diamonds, they can generally be provided upon request to help you evaluate your oval and see if it’s plagued with the oval diamond bow tie effect, and to what extent.

THE FOOLPROOF WAY TO MAKE SURE YOUR DIAMOND DOESN’T HAVE A LARGE BOW TIE

The best way to make sure your diamond doesn’t have a large bow tie? Work with an expert to find and source that perfect stone. Our gemologists can help you source, vet and select stones regardless of where you’re located. Text us at (646) 859-0718 or make an appointment online to book your free consultation today.

Don’t wan’t to talk to a salesperson? Browse our selection of diamonds. We offer one of the largest selections of lab grown diamonds available online, with more than 10,000 lab grown diamonds certified by the GIA and IGI, all in 360 degree video.