A diamond’s shape for an engagement ring goes way beyond round — take a look at your choices and how they set the style.
The first thing you need to know is that shape and cut are different, though related. The cut — one of the 4Cs along with color, clarity and carat — is the most important factor in determining how light reflects and refracts in the diamond, which creates the impression that it’s glowing from within. The diamond shape, though, determines the overall style of a diamond engagement ring.
The shape and how the diamond is cut in a round brilliant are inextricably linked. The brilliant cut is a complex formula designed to create the maximum beauty in a diamond.
When it comes to diamond engagement rings, the round shape is the most popular. In this instance, the shape and how the diamond is cut are inextricably linked — creating the classic round brilliant. The brilliant cut is one of the more complex cutting formulas, designed to create maximum beauty in a diamond.
The round shape transcends any setting or style of ring — it’s a true classic. Don’t judge a round cut by its carat weight, either. To get the brilliant cut’s dazzle, more of the rough diamond needs to be cut and polished away. So a smaller diamond, in terms of carats, may actually be more expensive and valuable than another that’s not cut and polished as well. Depending on its setting, you can often downgrade a bit in color grades with a round brilliant without sacrificing a bright white look.
The most popular square shape is a princess-cut. This is the runner-up shape in popularity for diamond engagement rings, behind the round brilliant. It’s often seen as a more modern or fashion-forward choice. The princess shape is a square design with a brilliant cut.
The princess-cut has pointed corners and is traditionally square, though it can be more rectangular. Because of the corners, if the diamond is set in a prong or elevated setting, it’s more vulnerable to damage caused by slight impacts (say, misjudging a doorway or digging in the trunk of your car) than a round diamond. So if the bride-to-be works with her hands a lot or is kind of clumsy, the square might not be the most practical choice.
The square emerald-cut, another geometric shape, is best when a diamond has few inclusions, because its “step-like” cut acts like a window, allowing inclusions to be more easily seen, so the clarity grade should be higher.
In a princess-cut and in a square emerald, color may be visible toward the corners, even in an almost-colorless diamond, so pay attention to the color grade and how it looks to you. The metals used in the setting, the band itself and whether there are diamonds or gemstones next to or surrounding the center diamond can also alter the perception of color, regardless of grade.
This shape is the go-to choice for celebrities, especially with big and/or fancy color diamonds. This shape has rounded corners and larger facets to increase its radiance. Cushion-cuts can be rounded-square to rounded-rectangular. The large facets of this shape highlight a diamond’s clarity.
The emerald-cut is defined by its special facet arrangement, which is cut with parallel facets to create a unique optical appearance. The top (the table) is large and open, and the special “step-like” cut highlights the clarity of a diamond. The emerald shape is traditionally rectangular, but the length-to-width ratio can vary.
Marquise diamonds can maximize carat weight, giving you a much larger-looking diamond.
Oval diamonds can vary in the length-to-width ratio — that shape difference is most noticeable when looking at its top.
For more information, please see the Jewelry Wise article What's the DIfference Between Diamond Shape and Cut?