Your Comprehensive Guide to Oval Cut Diamonds: From Quality to Purchase 

Oval diamonds, as the name implies, have an overall outline that is shaped like an ellipse rather than a circle. Non-round shapes are known collectively as ‘fancy shape diamonds’ and the oval is one of the most popular. It is distinctive and bright, and its elongated shape is graceful on the finger. The most common facet arrangement for oval diamonds is a brilliant configuration that is capable of producing excellent light performance (brilliance, fire and scintillation) if properly crafted. Oval cut diamonds are sought after by those looking for something different, yet still bright and showy. *Note: while this article is based on natural diamonds, the majority of the information presented below is also applicable to lab grown diamonds, with some distinctions which are discussed in the lab diamond section.

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The most common facet configuration is referred to as ‘oval brilliant’ on lab reports, and it looks very much like a round brilliant diamond that has been ‘stretched’ giving it a length clearly greater than its width. The actual length to width ratio can vary significantly providing a range of choices depending on personal taste. Some may prefer a rounder oval while others are attracted to a long slender shape. And while the optics are similar to a round brilliant, oval cut diamonds have the advantage of being less expensive than rounds of similar size and quality in natural diamonds.. Ovals are also versatile – perfectly lovely in solitaire styles as well as more ornate creations such as halo designs. They work particularly well as center stones in designs such as three-stone rings with oval diamond side stones, or with colored gemstones like ruby and sapphire which are most commonly cut in oval shapes.

Finding oval diamonds is easy - actually choosing one requires some additional knowledge. It is one of the most popular ‘fancy cut’ diamonds, but there are a number of complicating factors that make things a bit more challenging. When shopping a lab certified diamond, you will know the weight, size, color and clarity and can compare those factors against other potential candidates on the basis of their reports. But the most important value factor of any diamond is cut quality. This is where the diamond’s optics and light performance comes from. All the facets work together in a dynamic system of tiny mirrors that reflect and refract light and return it to the eye, resulting in brightness, scintillation, and fire. For a diamond to sparkle brilliantly, it must be cut well.

But most high quality loose oval diamonds come with lab grading done by the GIA. And GIA does not yet provide an overall cut grade for any fancy cuts (only on round brilliants), making it difficult for a consumer to know if the diamond is crafted to a level that brings out its full optical potential, or whether light performance suffers as a result of cutting deficits. The American Gem Society Laboratories (AGSL) does provide an overall cut grade on ovals, although you won’t find a wide selection on the market currently. (*learn more about light performance cut grading later in this article).

So, when shopping for an oval you will need to make other assessments beyond the GIA report. Fortunately there are tools available to help with that evaluation. There is of course in-person viewing. If you are able to see a selection of oval cut diamonds, some performance differences may be obvious and you may also be able to determine other important things such as color preferences and whether the diamond has any imperfections visible to the naked eye. When looking at diamonds, be sure to view them in different lighting environments.

But if you are shopping online you will want to take advantage of other diagnostic tools for assessing diamond light performance such as ASET, Ideal Scope, and HD video.

As mentioned, most natural oval diamonds are certified by GIA which leaves consumers without much information on overall cut quality. Presently, GIA only provides a cut grade on round brilliant diamonds. For reports on ovals, only the most basic data is provided pertaining to the cut – outer dimensions, table and depth percentage (see below). Polish and meet-point Symmetry grades are also provided. While this collection of information is useful in identifying the diamond, it is inadequate in communicating much about actual performance. As consumers in the information age have become increasingly more aware of and interested in cut quality, this shortcoming is significant. It is a particularly disadvantageous for the online shopper. Fortunately, more online merchants are providing advanced light performance images in order to fill in these blanks and give a fuller picture of how the diamond is handling light.

The American Gem Society Laboratories (AGSL) does provide sophisticated light performance grading on oval cut diamonds as well as several other fancy shapes. Unfortunately, there are not many AGS certified ovals on the market. Because the standard for AGS Ideal is so stringent, it takes more skill and time to achieve the top AGS grade. It also often involves greater weight loss from the rough. These are all elements that add to the cutters cost thereby reducing profit. Only those cutters dedicated to cutting entirely for beauty find it economic to cut to AGS Ideal. Therefore, oval diamonds with AGS Ideal certificates naturally command a premium in the market.

As a general statement, it is primarily branded proprietary ovals that are available with AGS Ideal certificates at the present time.

AGSL light performance grading involves sophisticated computerized light ray tracing and analysis. A platinum report will provide not only all the information contained on a GIA report, but much more. An overall cut grade is provided, along with grades for proportions, symmetry and finish. Grading is done on a 0-10 scale where 0 means Ideal (zero deductions). The AGS Triple Ideal is the highest laboratory standard in verified cut quality. The platinum report also provides an ASET light map of the diamond, providing additional information about how the diamond is handling light.

Because the market for oval cut diamonds is relatively small compared to round cut diamonds, and because the AGS Ideal standard is difficult to achieve by all but the most highly skilled diamond cutters, there are currently very few oval diamonds on the market that are AGS Ideal. But many online diamond vendors now provide ASET images on their diamonds.

One tool that has been used successfully for many years are charts with different parameter ranges broken down by cut quality categories. One of the most useful is a chart developed by renowned gemologist David Atlas and copyrighted by his former diamond grading lab Accredited Gem Appraisers, (AGA). Because all brilliant style cuts are similar, the following chart applies to pear shape, heart shape, and marquise as well as oval. They differ mainly in their preferred length to width ratios, which are separated within the chart.

It is important to understand the limitations of any parametric chart. First, you cannot make any meaningful determination of cut quality by looking at individual parameters. You must look at all parameters within a given classification as they work together. Secondly, basic proportions do not take into account facet precision which can significantly impact the actual light performance of a diamond. And lastly, parametric charts should only be used as a ‘rejection’ tool. That is, the charts can be used to filter out diamonds that have problematic proportions, but they cannot determine actual light performance. They help you focus in on diamonds that have the potential for good optics.

In the absence of comprehensive diagnostics and light performance imaging, using the chart can help render down a list of candidates. Once a candidate or candidates are identified, a well-equipped and knowledgeable jeweler should be able to provide the additional confirming diagnostics when the diamond is brought in-house for inspection. An ASET image is an important diagnostic tool that can help confirm light performance when interpreted properly.

One of the innovations that the American Gem Society Laboratories (AGSL) brings to the market is the ASET - Angular Spectrum Evaluation Tool. The view through the ASET scope provides a light map that tells you at a glance where the diamond is returning light to the eye and where it is leaking out of the back of the stone. It also reveals information about structured contrast and where the light is coming from that is being returned to the eye, which informs about brightness. ASET maps also reveal aspects of facet precision which indicate the level of cut craftsmanship.

In addition to actual ASET images, photo realistic computer generated ASET images are also available. The ASET tool can be used independently of an AGSL report, and a small handheld version of it is available to consumers for a reasonable price. Many good jewelers are capable of providing ASET images on the diamonds they sell, and many online merchants post them to their websites so that shoppers have this information up front. For more details see our dedicated page about ASET.

For shoppers that may be familiar with ASET images of round diamonds, particularly ideal cut rounds, ASET signatures of fancy cuts show much greater variation and require more experience to interpret accurately. Some leakages that would be considered deficits in a round brilliant, might not detract from the overall performance of a fancy cut such as an oval diamond. It is recommended that you consult with a jeweler or gemologist who has expertise in reading ASET maps in order to fully understand the diamond you are considering. Samples of various high performing oval diamonds below.

The length to width ratio of an oval diamond is a measure of how elongated it is. This has a bearing on light performance and it also has a more subjective visual effect with preferences that vary widely between people. Some like a rounder oval, while others like a long and slender shape. All other considerations being equal, this is purely a matter of personal taste. Most are likely to be in the 1.3 to 1.7 range.

Below are examples of oval diamonds ranging from 1.3 to 1.52, providing a sense of how the ratio impacts the overall shape and outline of the diamond.

Length to width ratio is calculated by dividing the length by the width. For example, an oval diamond with dimensions 9.60 x 6.94 x 4.36 (length x width x depth) has a length to width ratio of 9.6/6.94 = 1.38

One visual aspect common to most fancy brilliant style cuts is the ‘bow tie” effect. This is an area of darkness along the horizontal midline of the diamond. It can look like two triangles meeting at their points in the center of the stone, resembling a bow tie. Most shoppers want to avoid oval diamonds with pronounced bow ties. It is possible to cut ovals in a such a way as to minimize or eliminate the bow tie, but most ovals show this effect to some degree. Bow tie will be more pronounced upon closer inspection as the darkness is a reflection of head shadow, or in the case of macro photography, a reflection of the camera lens.

While there are a number of facet variations possible in oval, by far the most common is the oval brilliant. One version is patterned very closely off the round brilliant and consists of 57 facets including 8 main crown facets and 8 main pavilion facets. Another version has additional facets on the crown and pavilion, tending to produce smaller virtual facets and more of a ‘crushed ice’ look. The graphic below illustrates the difference in these two brilliant style arrangements. The facet arrangement on the left aligns the pavilion mains with the crown mains, and the arrangement on the right aligns the pavilion mains with the star facets, adding additional facets to the crown and to the pavilion in the process. The latter style is much more common. Face-up image, ASET and HD video of each style is shown below.

The plots below belong to two different proprietary ovals that feature an extra row of pavilion facets near the girdle. Both facet arrangements are stated on lab reports as ‘oval modified brilliants’.

There is some debate about whether an oval looks bigger than a round of comparable weight. Because the oval is ‘stretched’ some people believe they look bigger. The image below shows two sets of diamonds, one oval and one round, of almost exactly the same carat weight. All stones are very well cut. Take a minute to decide for yourself which ones look bigger. Below you will see calculations of the actual square mm face-up footprint of each.

By calculating the area of a round by the formula A=πr2 ,and the area of an ellipse by the formula A = π × major axis/2 × minor axis/2, the difference turns out to be extremely minor. In fact the ovals are very slightly larger, but by a factor of 0.1% or less. This is a virtually negligible actual size difference.

A more meaningful difference in real life may be actual light performance of the round diamonds vs ovals. Because the round brilliant has an almost perfectly symmetrical facet configuration, when ideally proportioned and cut with precision (such as the A CUT ABOVE® Super ideals in the photo), rounds have potential to return more bright light to the eye, thereby creating a larger visual appearance.

Color, one of the 4 C’s, is an issue to be aware of in oval diamonds. Depending on the facet arrangement and proportions of the diamond, an oval may concentrate color in the ends of the stone in a process known as color entrapment. This has to do with longer light ray path lengths and is one reason that fancy color diamonds are often cut in oval shape intensifying the color.

This is a factor to be aware of and to analyze carefully, particularly when considering an oval at the back end of the near colorless range or lower, and particularly for anyone who is known to be highly color sensitive. An oval of the same color grade as a round may reveal body color in the face-up view where a round does not.

Natural oval cut diamonds trade at prices lower than comparable size and quality round brilliants. However, it takes more effort to find a great buy on an oval, considering the importance of cut quality and the general lack of availability of such information on oval listings. If you are shopping for an oval you may end up getting a good price while also having to invest more time in your search.

All diamonds adhere to a pricing system based on the 4 C’s. And diamond prices tend to increase geometrically as diamonds go up in size, quality for quality. The most difficult part of the calculus is factoring in the appropriate value for Cut. Because lab grown diamonds do not have the intrinsic rarity that Earth-mined diamonds do, pricing is not tied to the 4C’s the way natural diamonds are.  But cut quality is still the most important factor in determining performance and beauty.

Making shopping more challenging is the fact that most retailers do not stock many natural ovals. So being able to see a wide selection in a store is generally not going to happen. And it’s important to understand that the bigger selections available in online catalogues are ‘virtual’ inventories. That is, the merchants offering them do not own them and in most cases have never seen them, much less had the opportunity to evaluate them. In many cases the diamonds are overseas. That is why it is important to deal with a company who has expertise in cut quality analysis and can provide the evaluations and advanced images necessarily to assure you that you are getting everything you hope for in your oval diamond.

In the past few years some significant technological advances are providing cutters with unprecedented abilities to craft precision cut diamonds. This will ultimately lead to more beautiful and interesting oval cuts as well as other shapes and facet arrangements that have not even been invented yet. With cutting technologies like the Lexus Galahad Compass now available, cutters can have precision control and predictability at their fingertips. With rough planning software like Octonus Oxygen and output diagnostics like the AGS light performance system available, cutters are armed with a set of tools with which to experiment and perfect standard designs and to invent new high performing diamond cuts. We are going to see a future full of unique and beautiful diamonds in an expanding array of shapes and facet arrangements.

Like the GIA, the AGS Laboratories are dedicated to consumer education and protection. But with their versatile and scientifically sophisticated light performance cut grade system the AGS is able to support the creativity and innovation of diamond manufacturing community by working with cutters to optimize their designs and maximize brilliance and fire.

Lab grown diamonds may also play a role in speeding the development of new diamond cuts. As synthetic diamond continues to become cheaper and cheaper, it will be possible for manufacturers to experiment. Putting this product before actual shoppers will inform them of which designs will have traction in the market and are worth investing in.

As mentioned above, lab created diamonds represent an affordable option in fine jewelry. Many engagement ring shoppers are also opting for lab created diamonds as it enables them to get bigger and better diamonds, as well as the possibility of getting premium designer brand settings for a given budget. Oval cut lab created diamonds are emerging as the most popular fancy shape.

Pricing of lab created diamonds is completely different from natural; significantly less expensive! The market is relatively young and rapid advancements in technology have made it easier and less costly for growers to manufacture bigger and better lab diamonds. Supply has been increasing and prices have been falling, and it is still unclear exactly where the market will settle out. Cost of production is the bottom line factor for any manufactured good, as opposed to a rarity factor that largely drives the natural market.

Whether or how much less expensive lab created diamonds might become in the future, they are already significantly more affordable than natural diamonds. And because lab diamonds are real diamonds with essentially the same physical and optical properties as natural Earth-mined diamonds, they can be just as beautiful and durable when fully transparent and cut with precision.

Finding a beautiful setting for an oval diamond is easy as excellent choices abound. All of the top designer brands have an ample selection of outstanding options for oval diamond rings and fine jewelery. The majority of designs made for round diamonds are also adapted to oval centers.

Whether you are looking for simple and classic, ornate and showy, or an antique or vintage look, you are sure to find lots of options in our designer catalogues.

Like most online retailers, Whiteflash does not stock oval diamonds. Our in-stock inventory of ideal and super ideal rounds and princess cuts is one of the deepest of any retailer anywhere. However, the ovals and other fancy shapes we provide through our Virtual Inventory Service are evaluated just as thoroughly as our A CUT ABOVE® Superideals. We evaluate the information available and help you identify good candidates. When we find one that meets your criteria, we bring it in and subject it to the same careful examination as our in-stock diamonds, including advanced imaging. That evaluation is shared with you and if you are not comfortable with the choice for any reason, we go back to the drawing board. In this way, any diamond you purchase through Whiteflash you will have a thorough understanding of, giving you complete confidence in your diamond purchase.

In addition, Whiteflash is an authorized distributor for all the major designer brands. The catalogue of available oval diamond ring designs, and the quality of those products, makes Whiteflash the go-to source for the finest in oval diamond engagement rings and fine jewelry.

We look forward to helping you have a brilliant experience in your diamond journey!