Oval cut diamonds have enjoyed popularity since the current form of the shape was developed in the late 50's and early 60's. The shape has the same number of facets as does the round brilliant. It also shares some similarity with the pear shape diamond, as they both produce a bow-tie effect. Oval cuts are classified as a modified round brilliant with the 58 facets being arranged similarly to round brilliants.
My wife likes the oval cut diamond shape as she says that it tends to make her fingers look more slender. The softness from the rounded ends is also one of the features she likes. Who am I to say otherwise?
While there seems to be a lot going for this shape it turns out to be surprisingly difficult to choose an oval cut diamond that has high light performance.
Here are some suggestions that can help you find a great stone when you are in the market for an oval cut diamond.
Length To Width Ratio
Symmetry and Polish
Understand the Bow-tie Effect
What About Cut Grade?
Color Guide
Choosing the Clarity Grade
Choosing a Setting
Length To Width Ratio
Once you begin searching for oval cut diamonds you will immediately notice that there are a number of different length to width ratios among these stones. Some oval cuts look slender and narrow, others look stout and fat. This means that there is plenty of room for personal preferences.
For the most part you will find that the majority of oval cut diamonds are somewhere between 1:1.4 and 1:1.5. An oval cut diamonds that is lower than that, say around 1:1.3 and it's going to look quite stout. On the other end the 1:1.5 ratios and over are considered narrow. These work well for earrings and pendants. The 1:1.4 to 1:1.5 ratio oval cut is the common ratio chosen as a center stone for engagement rings. If the ring has side stones then a ratio below 1:1.4 can also work.
Symmetry and Polish
You will no doubt have heard or read by now that the cut grade of a diamond is very important. The problem is that as of yet most grading labs do not issue a cut grade for oval cut diamonds. This makes is a bit challenging to find a well cut stone based on this aspect alone. The AGS does include a cut grade on their Diamond Quality Report. However not every jeweler has AGS graded oval cut diamonds. The most straightforward way to check for a well cut diamond is to find one whose grading report marks it as having excellent symmetry.
A grading report will show the quality, or grade, of an oval diamond's polish. A diamond's polish is very important no matter the cut (shape). This is why people place such importance on finding triple excellent diamonds: excellent cut, excellent symmetry, and excellent polish. It's the easiest and most straightforward way to find a great diamond. Even if this doesn't work for oval cut diamonds as you can't find a triple excellent oval cut at least you can find a double excellent oval diamond.
Understanding The Bow-Tie Effect
Due to the way the molecules of a diamond are arranged, diamond acts as both a mirror and a window. When part of a diamond returns all the light that enters it from a certain angle that area can look completely black. This is part of the magic of diamonds. They are very generous, giving back what almost seems like more light than they are given. In a round brilliant this can present a very attractive contrasting effect. In oval cut diamonds this presents as a dark band in the middle.
There is practically no oval cut diamond that does not have some sort of dark band in the middle. In most oval cut stones it presents as a bow tie. It's called the bow tie effect. The bow tie effect is usually preferred having a conspicuously large dark band. Some stones' bow tie effect is minimal. However whether or not an oval cut diamond has an ideal bow tie should be balanced with its overall brilliance and fire.
Remember that just because the light is not being returned to your eye in that central area of the stone does not mean it is not being returned at all. What you don't want is a stone that is leaking light through its sides and pavilion.
What About Cut Grade?
The shape of an oval cut diamond does not permit it to return light in a way that is comparable to a round brilliant. This is one of the reasons oval cut diamonds are 25-27% cheaper than round brilliants. AGS graded oval cut diamonds usually max out at 1 where the highest cut grade is 0. I am happy for someone to prove me wrong, but I haven't come across any AGS Excellent Cut Grade (0) oval diamonds. So don't feel like you are chasing a ghost if you don't find any AGS Excellent Cut Grade (0) lab diamonds. Or maybe do. There is no oval cut that can compete with ideal cut round brilliants.GIA is the lab of choice for a majority of diamond jewelers. This is due to the reliability and consistency of the reports they issue. GIA does not issut a cut grade for fancy cut diamonds, including ovals. They do however include some of the important measurements which experienced diamond handlers can use to identify a well cut diamond.
Here are my general cut parameters for the best oval cut diamonds:
Table: 51% to 64%
Depth: 58% to 66%
Girdle: Very thin to slightly thick
Culet: None
These are not hard and fast rules. Some diamond experts have slightly different recommendations.
An oval diamond can be brilliant, well-proportioned and beautiful in appearance but if you don't get a look at the diamond you can't be sure. Check out my list of places to buy oval cut diamonds online for some ideas on how to get a look at the diamond before buying.
Color Grade
A fascinating phenomenon we find in diamonds is that when they return light efficiently the color of the diamond becomes less apparent. Oval cut diamonds are the most efficient around the center area which has a similar to round brilliants. The color is usually harder to detect in the center area due to this effect. This means of course that a lower color grade, ie darker, oval diamonds are going to show distinct color phasing between the efficient area and the less efficient areas. That's not going to be an issue if the diamond is a D-E-F. Once you get past G the color starts showing more. G-H-I-J round brilliants don't show much color if they are ideal cut. Ovals from the H-I-J and lower color grades however can never look colorless no matter how good the cut because the geometry of oval diamonds will not permit it.The Best Clarity For Oval Cut Diamonds
All brilliant cut diamonds are dazzling enough to make inclusions difficult to see.
The sweetspot is VS2, just as with round brilliants, cushion cuts and princess cuts. SI1 and SI2 can sometimes yield good results too and it can be worth looking through these clarity grades for something that looks relatively eye-clean.
Choosing a Setting
Because the oval shape does not have any pointed edges, it is not as vulnerable as cuts that have pointed edges, like marquise or pear cuts. The classic setting for any diamond is the solitaire setting. For the best look, choose a prong setting as this allows for the maximum amount of light reflection and visibility of the diamond.Depending on the size of the stone, you can choose a 4 prong, 6 prong or 8 prong. Of course, the higher the number of prongs, the greater the security and the more accentuated the shape, but the lower the visibility of the diamond.
Another excellent setting for oval diamonds is the halo setting. This adds extra sparkle and maximizes the diamond’s look. A halo setting also tends to accentuate the elongated shape of the diamond and sets it apart from other diamond cuts.
Halo settings are popular for oval cut diamonds, as are three stone settings.
There are some beautiful vintage style designs around which work well too.
Some other great choices are three stone setting, side stone and pave. If you want something different for your oval diamond ring a tension setting might do the trick.
