A Diamond Shape Primer
What is it about diamonds that really captivates us? It’s not just the sparkle or color or size of the rock; rather, it’s a combination of the “4 C’s” and the way the diamond is set in the ring, earrings, pendant, etc. that gives us an overall experience of its beauty. While there is certainly much to say about color, clarity, carat, and cut — as well as different types of settings — we are going to focus here on one aspect of the diamond’s cut, also known as the shape of the diamond.
The shape of a rough diamond.
The Crowd-Pleasing Round
First, let’s meet the ever-classic, popular round brilliant diamond. This diamond is by far the most common of the diamond shapes and accounts for over 50% of diamond engagement ring sales today. It’s called round brilliant because this cut truly accentuates the facets of the diamond, thus letting the viewer see the rock’s brilliance. While rounds are popular and brilliant, they are not the most cost-effective of cuts since the yield from the rough (ie, how much diamond is left from the original piece of rough after cutting) is only 40%. That lower yield-from-rough ratio is then passed on to you, the consumer. Imagine taking two 4 sided pyramids and sticking them together at the base — the result is called an octahedron. That’s what rough diamonds look like. Try getting a round diamond out of that shape and you’ll see there’s a lot of diamond simply cut away. Yield-from-rough isn’t something you, the consumer, need lose sleep over; yet I do feel it’s important to understand why different shapes cost more than others.
A GIA certified 1.01 Carat G Color VS2 Clarity Excellent cut Round will cost approximately $8,600 online.
The Runner-Up Princess
Second, let’s look at the next most popular diamond shape on the market today. The princess cut accounts for about 23% of diamond searches on one popular diamond e-retailer site (after the round brilliant at 64%). The first thing you notice about princess cuts is their rectangular shape — in stark contrast to the curvy round. While aesthetically this may suit your tastes better, it’s a much better deal for the diamond cutter. The yield-from-rough value of the princess cut is 80-90% and was invented exactly for the purpose of getting as a high a yield as possible. Think back to the octahedron; if you cut your eight-sided rough in half, you basically end up with two princess cut diamonds. This is also why princess cuts are cheaper than round cuts (keeping all other variables constant).
A GIA certified 1.01 Carat G Color VS2 Clarity Excellent cut Princess Cut will cost approximately $5,300 online.
The Elegant Emerald and the Alluring Asscher
After round brilliants and princesses, the emerald cut finishes a distant third with only about 3% of online searches, followed by Asscher cuts with 2%. Emeralds and Asschers are known as “step cuts.” They are either square or rectangular shaped and usually have rounded or softened corners with an octagonal outline. The corners are rounded so that they don’t chip or fracture, thus giving these stones the same cut look as the green emerald stone. Because these are not brilliant cuts, you will not see the same fire and sparkle as you would with round or princess cuts. Instead, these shapes are known to show off the diamond’s clarity and white color.
But what’s the difference between the square emerald and Asscher cut diamonds? People often ask me this question. Basically, there are two kinds of Asschers — the standard and the royal, both invented by the Royal Asscher company. The former is the older and un-patented design with 58 facets. This is what we call today the “square emerald cut” or the “Asscher cut.” By contrast, the Royal Asscher cut boasts 74 facets and a high crown, and is an exclusively Asscher patented design.
A GIA certified 1.01 Carat G Color VS2 Clarity Excellent cut Emerald Cut will cost approximately $5,000 online.
The Contemporary Cushion
Another trendy shape today is the cushion cut diamond. While it may be popular, it’s the least understood of the shapes. There’s a lot of confusing and conflicting advice out there about cushion cuts. Basically there are two types of cushions — the older and more conventional “standard cushion” and the more modern “modified cushion.” The differences between these two types of cushions are not all that great; they are simply two slightly different ways of cutting cushions.
What is more important is the look that you want. We’ll call these the “chunky” cushion and the “crushed-ice” cushion. While these two types of cushions look noticeably different, this difference is NOT due to their being standard or modified, as many people mistakenly think. So what is crushed ice versus chunky? Crushed ice, or broken-glass, cushions have no discernible faceting; instead all you see is a lot of sparkling bling. Contrast this with the chunky, or antique, cushion that does have easily defined facets and you’ll see that it looks more like a round brilliant.
A GIA certified 1.01 Carat G Color VS2 Clarity Excellent cut Cushion Cut will cost approximately $5,500 online.
Honorable Mention
And we would be remiss not to mention the lesser known though no less dazzling diamond shapes that you may encounter in your diamond shopping: pear, oval, heart, radiant, and marquise. These shapes are certainly more unique than your regular round or princess. Ultimately, it comes down to a question of style and taste.
Follow the Herd or Go with Timelessness
While round diamonds have always been the most popular shape, certain other shapes always seem to rise and fall in waves in terms of popularity. Ten years go, princess cuts surged in popularity. Nowadays, it’s cushion cuts that are all the rage. So this is another thing to keep in mind – do you want to buy a shape that’s popular now, or do you want to buy something timeless?
Brilliant, Man!
Well now that you know what your options are, see which of these shapes tickle your fancy. Try to find out what tickles her fancy as well. Maybe try casually asking her as you stroll past a jewelry store. You might want to try asking her close friends.
Once you select a shape, it’s time to do your homework on what clarity, color, and carat size would complement it best. Remember, be an informed consumer: get the best looking diamond you can without paying for unnecessary features you can’t appreciate with the naked eye. Knowledge, and in this case brilliance, is power to the people. 
Ira Weissman+ is a diamond industry veteran with a decade of experience at one of the world’s largest diamond polishers. He has traveled the world buying and selling diamonds and now dedicates his time to helping consumers make the most of their diamond buying decisions. He has been featured on Anderson Cooper, CNBC, and has been quoted by MarketWatch, The Village Voice, and BankRate. Visit Truth About Diamonds to educate yourself about diamonds.