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Ask a Diamond Pro: Choosing a Square Cushion Cut Diamond

By Mike Fried,

When it comes to diamond shapes, most people opt for the conventional round brilliant cut due to its brilliance (the ability to reflect and refract light) and versatile appearance. 

However, we often receive emails from readers interested in other diamond shapes, particularly eye-catching, elegant options such as the cushion cut and princess cut. These diamonds offer a unique appearance and often superior value for money when compared to the round cut. 

Buying a fancy shape diamond offers certain advantages, but it also presents some challenges, especially when it comes to assessing diamond cut quality. 

Recently, a reader contacted us seeking help finding and buying a cushion cut diamond in the 1 carat range. They were interested in a diamond with a fairly square shape and wanted to spend around $7,000 in total. 

As is common with cushion cut diamonds, they also had several questions about cut quality and color.

Here’s the reader’s email:

“Great website. I found it very useful in researching the diamond buying process. 

I am looking to purchase a cushion cut diamond, around 1 carat and would like to keep the cost around $7,000 (USD). I have read your website and am thinking that the Signature series from Brian Gavin could be a good option. 

If I were to purchase a Brian Gavin Signature diamond would you still suggest that I purchase a cushion cut diamond that is “H” or above in terms of color, or would “J” be acceptable? Would it be better to purchase a non-signature series diamond with better grade in terms of the color and avoid the signature series with the “J” color grade? 

Any advice would be much appreciated. Additionally, if you have any other suggestions in terms of comparable quality diamonds from other retailers such as Blue Nile or James Allen I would love to hear them. 

Thanks for the help!”

These are great questions, and this reader’s idea of choosing a Brian Gavin Signature diamond for cut quality is also an excellent idea. 

Brian Gavin Diamonds specialize in outstanding cut quality. For this reader, a diamond from the Signature Hearts and Arrows range would guarantee extraordinary brilliance and result in a ring that looks stunning in any lighting conditions.

When it comes to optimal diamond color, it often depends on the setting. Because a cushion cut diamond will show color more than a round cut, it’s best to stick to a color grade of H or better unless you plan on choosing a yellow or rose gold setting (in which case I color is alright).

We’ve gone into more detail about this reader’s questions below and provided some information to help you make an effective, informed purchase if you’re considering a similar diamond.

Choosing a 1 Carat Cushion Cut Diamond

The cushion cut is an interesting diamond shape with lots of unique advantages. It combines the modern facet pattern of the round brilliant cut with that of the old mine cut — an antique diamond shape famous for its square form with rounded corners.

Cushion cut diamonds have excellent brilliance and fire, as well as greater durability than other square or elongated diamonds due to their rounded corners. 

Because less of the rough diamond is wasted during the cutting process, the cushion cut is also more affordable per carat than many other diamond cuts, particularly the round brilliant. 

This reader’s budget of $7,000 is more than enough to find a gorgeous cushion cut diamond in the 1.00 carat range. 

First, let’s start with cut. As we mentioned earlier, the Brian Gavin Signature Hearts and Arrows range is the best choice here, as it’s limited solely to diamonds that conform with the strictest of cut parameters. 

In fact, Brian Gavin himself — one of the world’s experts on perfectly cut diamonds — personally selects the company’s diamond range for optimal brilliance. 

Our review of Brian Gavin Diamonds goes into more detail about how their selection differs from that of other diamond vendors. 

This strict selection process is important for a cushion cut diamond, as there is no cut grade, such as “Excellent” or “Ideal” on its GIA or AGS certificate. 

An exceptionally well-cut diamond will come with a slight price premium. However, because cut has such a big impact on the beauty and perceived size of a diamond, we think it’s a premium that’s generally worth paying.

4ct cushion cut diamond
A proposal with a cushion cut diamond ring

An alternative option is to choose a diamond from James Allen or Blue Nile after paying careful attention to its cut quality.

James Allen and Blue Nile both offer a variety of stunning cushion cut diamonds. For example, this 1.01 carat, H color, VS1 clarity diamond is very nicely cut, colorless and free of any visible inclusions — an important topic we’ll discuss below. 

Carefully assessing cut quality is especially important when it comes to the cushion cut. This is because, as a fancy shape diamond, the cushion cut doesn’t come with a single cut grade from the GIA that you can use to determine its cut quality. Instead, being that it’s a fancy shape diamond, you’ll need to carefully review its cut yourself to check that it has good proportions and light performance.

As diamond industry insider Greg Kwiat notes here in an interview with Rapaport, “there are so many poorly cut diamonds in the cushion shape.” If you choose to go the James Allen or Blue Nile route, it’s essential to understand what makes a cushion cut diamond well cut and attractive.

This is a topic we’ve discussed more in our guide to the cushion cut, along with information on the key parameters to look for in a diamond of this shape.

Now, let’s move on to diamond color and clarity. Because of the large open table of the cushion cut, this type of diamond is more likely to display imperfections and internal color than, say, the round brilliant cut.

This means that it’s important to be selective and carefully check that your choice of diamond is eye-clean (meaning it has no visible inclusions) and free of any obvious internal color. 

When it comes to color, a grade of H or better will ensure that a cushion cut diamond looks free of any visible color in its setting. It’s especially important to stay within the H+ range if you plan to pair the diamond with a setting that features other diamonds, like a pavé or side-stone ring. 

This reader mentioned a preference for a pavé platinum setting in a later email, making the H+ color range the best option due to the pavé diamonds and white color of the metal. 

Cushion cut in a pave setting graphic

As for clarity, we generally recommend going with the lowest clarity grade that still provides an eye-clean diamond. For a cushion cut diamond, this usually means a clarity grade of VS1, VS2 or SI1. 

As always, regardless of clarity grade, it’s important to check the diamond for inclusions using the high-resolution images provided by James Allen and Blue Nile. If the diamond has visible inclusions — especially inclusions near the center of the table — it’s generally best avoided.

Our Recommendation

In the end, this reader chose this stunning 1.05 carat, H color, VS1 clarity cushion cut diamond and paired it with a beautiful pavé setting. It’s an excellent diamond, and by prioritizing its most visible aspects — in this case, cut quality — it also offers fantastic value for money.

If you’re considering a cushion cut diamond, it’s important to choose one with an excellent level of cut quality — something that’s easier said than done due to the lack of information offered by most cushion cut diamonds’ GIA or AGS certificates. 

Because of this, we recommend using the cut parameters in our cushion cut diamond guide as a starting point if you’re considering this shape. 

As always, you can also contact us for help finding and choosing a diamond. Our team assists hundreds of our readers every month, and we’re more than happy to help you find the diamond that matches your tastes and budget.

James Allen James Allen is the leader in online diamond sales. Their imaging technology is the same as inspecting a diamond with a jeweler's loupe. They have the largest exclusive loose diamond inventory online and fantastic prices. They also have the nicest collection of lab created diamonds online.
What we love about them:
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Blue Nile Blue Nile is the largest and most well known internet jewelry seller. They have a very large exclusive online inventory. Their high quality images are catching up to James Allens' and their prices are amazing.
What we love about them:
  • No questions asked returns within 30 days of shipment. Blue Nile will send you a paid shipping label to return the ring.
  • Lifetime Warranty
  • Free Shipping
  • Free prong tightening, repolishing, rhodium plating and cleaning every 6 months
  • Provide insurance appraisal
  • One free resizing within the first year of purchase
  • High quality images of about half of their diamonds
  • 24/7 Customer Service
  • 100% credit towards future upgrades (must be at least double in value)
  • Best in class fulfillment
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