Diamond Shapes 101


Whether you’re choosing a diamond shape for an engagement ring, earrings or a just for fun ring, much more goes into it than mere aesthetics.  To my horror, there are a host of issues that no one tells you.  For example, some diamond shapes hold more weight than others–meaning, for the same carat weight, certain shapes will look smaller because the bulk of the weight is in the lower part of the diamond that is hidden by the setting.  Similarly, certain shapes will reflect light better than others due to their shape and cut and as a result, certain shapes will be more brilliant than others or show more fire.  Here is everything you need to know:

Basic Diamond Shapes

Diamond Shapes 101

Round brilliant shaped diamonds are the industry standard–they have 57 or 58, mostly triangular, facets (depending on whether you count the culet as a facet).  Round brilliants are the most scintillating because of the way that light reflects off the facets.  Anything that is not a round brilliant shape is considered a fancy shape.  Many people confuse shape and cut.  In the industry, the term shape is used to denote the actual shape of the stone whereas the cut is a term used to describe how well the proportions, symmetry and polish of the stone are executed.  In other words, shape is a personal choice whereas the cut speaks to the quality of the stone and is thus, non-negotiable.

Emerald shapes are step cuts, made up of a series of rectangular facets parallel to the girdle.  In general, emerald shaped diamonds are not as brilliant and do not show as much fire (the flashes of color you see when you move a diamond under a light source) but they do highlight a diamond’s clarity, which could be positive or negative.  If purchasing an emerald shaped diamond, it is better to select one with a high clarity grade as any inclusions will be more visible in a step-cut stone.  Furthermore, with emerald cuts, it is important to have your jeweler make sure the proportions are ideal.  There is a tendency in emerald cuts for the stone to be too thin or too thick either in the crown height or the pavilion depth.  In the first instance, a stone that is thin will look larger face-on but in such situations you are sacrificing visual properties and durability.  If the diamond is too thick, then you are hiding weight in the pavilion and the result is that you are paying for a stone that looks smaller than its carat weight would suggest.

Marquise, princess, pear, radiant, Asscher and cushions all fall into the category of fancy shapes.  Some are considered modified brilliants and some mixed cuts (having a combination of brilliant and step cuts).  In general, cushion shapes look smaller than their carat weight lets on because the stone has to be cut slightly thicker so there is more weight in the depth of the stone than you see on the surface.

For the most part, your jeweler should have very strict standards about what stone she uses and should have inspected and vetted all the diamonds before you see them.  Obviously, when buying a stone we want to strive for perfection in cut (symmetry, proportions and polish).  However, here is a little list of common concerns and what to prioritize with respect to each shape:

Rounds– Proportions need to be bang-on.  The crown height vs. the pavilion depth should be such that you are maximizing the diamond’s fire, brilliance and scintillation.  If you are buying a certified stone, the cut grade will tell you all this.  Strive for very good to excellent cut grades (the scale: Poor, Fair, Good, Very Good, Excellent).

Princess– Symmetry is key.  Make sure all sides of the stone are parallel.  From a face-on view, a princess cut has to look like a perfect square, if the sides are wonky and it looks more like a trapeze or rhomboid, walk away.  Princess cuts have very defined points on the corners, have your jeweler make sure they are pristine.  Sometimes the corners are chipped during setting and the chips are hidden by prongs.

Marquise– Symmetry is a big one here as well.  You’ll want to make sure that if you draw a line down the diamond both left and right sides match and if you draw a line across the diamond, the top and bottom halves match (ex: you don’t want the top two sides to bulge more than the bottom two and vice versa or the left side to bulge more than the right).  Keep an eye out for bowtie shadows.  All marquise and pear-shaped diamonds will have shadows in the middle of the stone that resemble a bowtie.  The better the cut of the stone, the smaller the bowtie shadow.  If there is a distracting gray bowtie in the center of your stone walk away.

Pear Shape- It has to be pretty.  With a pear shape symmetry matters but you have to decide whether you like a stone that looks like a chubbier drop or a thinner one.  I prefer chubbier drops but it has to be within reason.  Eye-appeal is crucial here, if the stone looks too heavy on the top or bottom it’s not cut well.  Don’t forget to check for the bowtie shadow!

Emerald and Asscher– Symmetry, look for parallel lines, make sure the keel is even down the diamond in an emerald shape.  There should be no glaring inclusions that you can see with the naked eye.  Have your jeweler check to make sure none of the edges are chipped.

Radiant and Cushion- Proportions and symmetry should be stressed.  Check to see that all sides are even and symmetrical, similar to the marquise, all 4 sides and 4 corners should have the same curve or bulge.  If you imagine folding the diamond into 4ths, each corner should match.  No wonky corners or sides.  Proportions are a big consideration here as well, as explained earlier, we don’t want a bottom-heavy stone–that just means you’re paying for a stone with hidden weight that you can’t see once its set.

That little cheat sheet should get you through your diamond buying but if you have any questions email me or leave me a comment.

Big Kiss and Bigger Diamonds,






  1. barbara8max says:

    I think you are converting me to liking diamonds. I am starting to believe that the reason I’ve never been drawn to them is for all the beware of/be aware of reasons stated above.

    1. Barbara, there is an amazing book called Jewels: A Secret History. I think you would like it. It speaks of all the history, superstitions and tales of many different jewels and stones. It’s enlightening and when you read it, it’s easy to forget about all the unflattering marketing schemes that surround stones. It highlights their mystical and historical properties and reminds you of the true purpose of jewels: to dazzle and transport us to a dreamier reality.
      Big Kiss and Bigger Diamonds,