Cushion cut diamonds fall into many different categories but only one of them really dominates the market: Cushion Modified Brilliant. While there are a variety of other cut types including Cut-Cornered or Round-Cornered, Rectangular or Square, Brilliant or Modified Brilliant cushion cut diamonds (not to mention Old Mine Brilliant), you should know that about 97% of the inventory we've studied from online jewelers is simply Cushion Modified Brilliant. Cushion Brilliant comes in a distant second at 2% of the sample. Cushion Modified Brilliant can be further classified as either "crushed ice" or "chunky", we'll break these down more later.
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Cushion is one of the most popular shapes of diamond cut but it still pales in comparison to the popularity of round diamonds in terms of how much selection you'll see available at online and physical jewelers. That said, there are still thousands of options available on most major online jewelers. Cushion cut diamonds do not receive a cut grading from the GIA the way round diamonds do, but there are some specifications you should try to stick to when shopping.
We recommend you consider VS2 or better clarity, look at I or better color for platinum settings (K or better for gold settings), Depth between 58.5 and 67, and Table between 56 and 65, Girdle should range from Very Thin to Slightly Thick. For polish and symmetry you should stick with Very Good or Excellent Grades. Most importantly - you need to see the diamond to make sure that the diamond looks the way you want it to by checking out videos and images.
Cushion is among the most popular diamond shapes, but still commands a significantly lower price point than round diamonds. Above is a chart depicting the price (y-axis) trend for a large population of H VS2 cushion cut diamonds (GIA certified very good or better polish & symmetry). The price trend was solved using a simple regression on a the data set – our pricing algorithms use a more sophisticated machine learning algorithm than this model and incorporates several additional factors including each diamond’s specific dimensions.
However, for studying simple price trend the above will paint a simpler picture. As you can see, a 1 carat H VS2 cushion cut diamond costs approximately $3,500 while a 2 carat costs approximately $13,500. This exponential growth in price (the price more than doubled when the size doubled) is due to the diamond pricing metric that most jewelers cite when discussing value: price per carat. Every diamond shape exhibits a similar exponential price trend as carat size grows larger. This is summed up by saying, “the price per carat increases as the carat size increases”.
StoneAlgo always recommends you consider GIA Very Good or Excellent polish & symmetry grades for cushion cut diamonds to ensure your diamond looks its best - but what about cut? The GIA does not currently grade the cut quality of fancy shapes like they do for round cut diamonds. Instead, as buyers we have to focus on some rules of thumb and, most importantly, visual appearance. Beyond simply recommending very good/excellent symmetry & polish, we conduct an algorithmic study of diamond dimensions to make sure that every diamond you see on our site is within the ideal table/depth dimensions.
A general rule of thumb is that you don't want the table or depth to be above 70%, but many jewelers recommend slightly more stringent parameters. At the end of the day the biggest consideration from a cut standpoint is whether you want the look of a crushed ice or a chunky cushion cut. It's totally a matter of preference though, the chunky will have defined facets and should offer superior light performance. The crushed ice look is also very nice but you may want to pay a little more attention to color here, on the flip side they hide inclusions better than a chunky cushion.
Cushion cut diamonds aren't graded on cut like round diamonds are, but the AGS does score the light performance of cushions and we recommend you check out some of Brian Gavin's amazing cushion cuts if you want to see examples of high cut quality in a cushion. Below are some general ranges StoneAlgo recommends for Cushion Modified Brilliant.
When it comes to cushion cut diamonds, we generally recommend that you begin by looking for an I or better color grade if you're choosing a platinum setting and a K or better color grade if you're choosing a yellow or rose gold setting. Additional considerations should be made depending whether you choose a crushed ice or a chunky cushion cut. For the crushed ice cushions you may want to improve the color grade slightly as these tend to retain color a little more than the chunky cushions do (meaning an I color chunky will look a little whiter than an I color crushed ice if all else is equal). If you are going for a very larger carat size (say 2 carat or more) you may also want to consider better color grades. However, there are a lot of great examples of larger cushions where an I color looks very white in a platinum setting.
Clarity is the toughest aspect of a diamond to judge simply based on a diamond’s grading certificate alone. Two diamonds of the exact same size and clarity grade can look totally different depending on the types of inclusions in the diamond and where they are located. Generally speaking, these differences in appearance are not relevant in the better clarity grades like FL, IF, VVS1, VVS2, VS1, and even VS2 clarity – though occasionally a VS2 clarity will not be as eye clean as you may expect it to be. On the flip side, SI1 diamonds can appear totally eye clean when they have inclusions in a certain location where it is less visible. Eye clean means that a diamond looks flawless without the aid of magnification from a jewelers loupe or microscopic lens. Here’s an example of a 1.02 carat F color SI1 clarity diamond that doesn’t appear to be eye clean (click to see a 360 degree video that shows the black speckled inclusion even more).
Compare the above image to the below picture of another 1 carat F color (but this time eye clean) SI1 – the diamond received an SI1 grade due to some internal graining not shown as you can see by clicking the diamond and viewing its GIA certificate. This type of inclusion is tough to see even under magnification and is a good example of why eye clean SI1 diamonds are the most sought after when buyers are trying to stretch their engagement ring budget. We would note, however, that eye clean SI1’s typically cost about the same as VS2 clarity diamonds and sometimes even more – don’t simply trust that due to the grade you are getting a good deal!
Diamond fluorescence produces a glowing property in some diamonds when they are exposed to ultraviolet light. To give an example of how prevalent fluorescence is in the diamond market, this affect is present in about 35% of the diamond inventory available at Blue Nile currently. Fluorescence is not necessarily a good thing or a bad thing, but like most things in life it’s good in moderation or in certain situations. Check out all of the fluorescence stats here.
For example, if you are buying a colorless diamond (D – E), then fluorescence may not be a good thing. But for diamonds grade I – K and lower, faint or even medium fluorescence can actually help the diamond appear whiter. Strong fluorescence is typically not recommended as it can make the diamond look hazy – so we’d recommend you stick with faint or none to be safe. You may have seen the designation negligible fluorescence which is the AGS grading equivalent to the GIA’s “none” qualification – representing diamonds that do not exhibit fluorescent properties.
That concludes our general recommendations for cushion cut diamonds. There are a lot of moving parts but generally speaking we try to maximize carat size for our given budget by sticking to the lower end of the color ranges we specified and searching for VS2 or better diamonds. SI1 diamonds are great if they’re eye clean, but they are a pain to find and often end up costing just as much as a VS2 diamond would. If you need one-on-one advice, we offer free support to all our users – simply drop us a line at firstname.lastname@example.org.