My philosophy in buying diamonds is that CUT is always king. This is because cut quality determines how much sparkle the diamond has and it mitigate shortfalls in other aspects of the 4Cs.

You see, better cut quality results in better brilliance and sparkle. This helps to mask inclusions and improve face up color of the diamond. On top of that, well cut diamonds look bigger because of better edge to edge brightness.

For these reasons, I recommend shopping within BlueNile’s signature collections since the diamonds have been curated for better cut quality.

*Update 2018: Blue Nile has rebranded their signature diamonds and labeled them “Astor”. Instead of GCAL reports, Astor diamonds are now accompanied by GemEx Diamond Light Performance reports.

On the whole, it is just a rebranding exercise and the overall quality of Astor is kept at identical standards to their previous signature diamonds.

BlueNile’s Signature Diamonds – The Different Shapes Available

At the time of writing this review, Blue Nile offers 5 shapes of diamonds for their signature lines;  round, princess, emerald, asscher and cushion hearts & arrows.

blue nile signature diamond shapes

The collections are accessible via their drop down navigation menu.

When I did my research and browsed through the signature diamond collections, I am actually pleased to see that they are generally well cut for light performance.

Most notably, the emerald, Asscher and cushion hearts and arrows inventories stand out for their depth of diamonds offered. Now, I can tell you this is a feature no other vendor (both online and offline) can come close to matching.

As a result, I was able to find good choices of diamonds across various carat sizes and budget ranges. Check out some of the outstanding diamonds I found below. If you want to find out more details about any individual stones, simply click on the corresponding images.

1 carat cushion hearts and arrows review

Blue Nile’s signature cushion diamonds display superb scintillation and contrast patterning similar to those offered by ideally cut rounds. This particular 1 carat cushion hearts and arrows diamond is a rare breed that offers good value for money.

half carat asscher cut diamond

Well cut Asschers are really hard to find because most are cut for weight retention instead of optical performance. This half-carat D VVS2 diamond is a fine example of one that would pass my standards to be purchase worthy.

half carat emerald cut diamond review

Like Asscher cuts, emerald shaped diamonds that display good brightness and scintillation are very rare. Blue Nile does a great job in setting high standards for their signature emerald cut diamonds.

0.70 carat princess cut

Princess cut diamonds are the 2nd most popular shape in the industry after the traditional round brilliant cut. If you are buying a princess cut diamond, you want to ensure that the girdle thickness is above a thin rating for better durability.

In this particular example, I picked out a colorless diamond with eyeclean SI1 clarity. And the good news is, it’s just one of the many that are available in their signature princess cut diamond collection.

As you can see, you can find extremely well-cut diamonds at Blue Nile at very competitive prices. Click here to visit and start browsing for your own diamond ring now!

How to Select the Best of the Best Signature Diamonds?

It’s great that BlueNile has curated diamonds for cut quality before they get listed in their signature lines. This means that 90% of the work has been done for you.

However, every diamond is unique and there is always going to be some variances in cut quality. To cherry pick the very best of the best, you do need to perform a little work and some diligence.

Don’t worry, I’m going to walk you through the steps with some real life examples. Once you understand the things to look out for, it’s actually a pretty straightforward process…

Step 1: Use Videos to Determine Eyecleanliness

The majority of diamonds will contain inclusions since they are naturally formed deep inside the Earth. You need to understand that it is perfectly OK to buy a diamond in the lower clarity range as long as the inclusions are eyeclean.

Here’s a fact; In terms of clarity, 99% of people cannot tell the differences between an eyeclean SI1 diamond and an IF diamond. Think about it, why should you pay a huge cash premium for an internally flawless diamond when can’t see inclusions with the naked eye?

Now, I’m sure the next question that comes to mind is; how do you determine eyecleanliness when buying online.

Well, I got you covered…

Read this proven step-by-step method that hundreds of readers had successfully used for their diamond selection. Once you had done that, all you need to do is to apply the knowledge to your own shopping.

Step 2: Refer to GCAL Report to Assess Cut Quality

Remember I said Cut is King earlier? I also mentioned you need to base your buying decision on facts and tangible information.

Let me show you how to perform an assessment of cut quality at BlueNile.

When reviewing a signature diamond, you can refer to the accompanying GCAL report to determine its cut precision and optical performance. You can do this by looking at the data under the “Hearts And Arrows”, “Optical Brilliance Analysis” and “Optical Symmetry Analysis” headers.

I listed an example of a diamond that passes my standards to be purchase worthy. Feel free to click on the image below and review the GCAL certificate I highlighted below…

analyzing a signature diamond from bluenile

gcal report review

To help you get a better idea on things to look out for, I had also included an example where the cut quality doesn’t pass my standards. Check out the extracted info from the GCAL report below…

review of gem certification assurance lab certificate

GCAL data reveals light leakage and inconsistencies in facet precision.

Indepth Review of Blue Nile Signature 1 Carat Round Diamond 

Recently, I purchased a halo engagement ring from Blue Nile. Using the steps above, I chose a 1 carat F color SI1 clarity diamond. You can view details of the stone below…

1 carat diamond bluenile f si1 $10000 dollars

Here’s a copy of the GIA report for your reference.

gia round brilliant one ct f si1

I had also extracted the relevant information from the GCAL report here:

bluenile gcal report review

As further proof that the 2-step method works, I captured the following Idealscope and ASET images of the diamond. Both photos indicate a diamond with very strong light performance.

idealscope image bluenile round 1 carat

Idealscope image

aset image bluenile round cut signature

ASET image

A Video to Showcase the Diamond’s Performance



Overall, I’m very pleased with the outcome of the diamond ring purchase. Once you understand the things to look out for, selecting a beautiful diamond from Blue Nile is pretty easy.

Click here to start browsing for your own engagement ring! If you need help in your diamond selection, feel free to get in touch with me and I’ll do my best help you out.

On the next page, we will round up our review by performing an analysis on the craftsmanship of their ring setting (lots of pictures included!). I also made an unboxing video to show you the exact package you can expect to receive from BlueNile…

Related Articles’s Astor Diamonds Receives a Good Rating of 4/5 – Reviewed by

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  1. Nick-
    February 5, 2015 at 7:46 pm

    What do you think about Blue Nile’s line of signature ideal asscher diamonds?

    I have currently shortlisted 3 E colored stones around the range of 0.7 carats. I would like to seek your opinion on these diamonds and what you think about them.

    You can view the images in the GCAL report and can you offer any insights to the optical light performance profile for the diamonds?

  2. Paul Gian-
    February 6, 2015 at 2:11 am

    The images found in the GCAL report have poor resolutions. Anyways, stone #2 is a bad choice due to light leakage under the table. I would definitely avoid it. The other 2 diamonds look OK but aren’t great. I would say that you can do far better when it comes to Asscher cuts instead of buying a BlueNile signature which has a lack of consistency in cut quality.

  3. Darryl-
    February 16, 2016 at 7:59 pm


    Great insight in the pages here. I’m working with a company called Adiamor. What do you know about them and are they reputable?


  4. Paul Gian-
    February 17, 2016 at 1:46 am

    They are a legitimate company like Blue Nile but the problem is that Adiamor is pretty much the same like Blue Nile when it comes to the lack of information they provide on their listings.

  5. Sal-
    June 14, 2016 at 4:51 am

    Hi. I am glad I found this page as I was considering Blue Nile. I am a special ed teacher on a budget and want to get my girl a nice enough ring. How do the blue nile astor diamonds compare against james allen’s truehearts?

    Can you help? Thanks!

  6. Paul Gian-
    June 14, 2016 at 5:00 am

    Sure. Let me know what you are looking for. You might want to email me directly as I check my email more frequently than the comments here. In general, Blue Nile’s astor signature diamonds don’t have the same level of cut precision and performance of James Allen’s truehearts.

  7. Tony-
    April 9, 2017 at 5:40 am

    The diamond you said you purchased is actually still available on Blue Nile. Did you trade-in the diamond again for upgrades? This means Blue Nile is actually selling 2nd hand diamonds. Hmmm… Something is not quite right here.

  8. Paul Gian-
    April 10, 2017 at 4:55 am

    I actually mystery shopped at to perform this review (I actually do it at alot of vendors frequently to test them out). Sometimes, I may keep the ring for my wife as a gift like what I did here:

    This BlueNile purchase was made very near the purchase of the colored diamond ring from Leibish. Since my wife has already received the colored ring, I decided to return the BlueNile purchase. That’s the reason why you see the diamond being relisted for sale at BlueNile.

    Basically, I bought, examined and reviewed the product and also tested their support services when sending the items back. BlueNile passed the various aspects I look out for and this is the reason why I’m comfortable recommending them to readers.

  9. Kahsha-
    June 8, 2017 at 9:57 am


    Thank you so much for all of the fantastic info. I am looking for a diamond for an engagement ring. Somewhere between the .80-.95ct range. I’ve found this one in Blue Nile that I quite like. I’m hesitant to go for a Si1 diamond as I’m just too scared it will have visible inclusions. I’ve tried to use all the info I’ve learned to spot them .. but my eyesight must just be rather bad.

    This is what I’m looking at .. thoughts? I’ve chosen this one as it is sig. ideal and therefore I feel more confident that it will be nice. However, I wouldn’t mind having a slightly bigger diamond for less money if I was better at looking at the diamond.

    Thank you so much

  10. Paul Gian-
    June 8, 2017 at 3:57 pm

    You did well to pick out this diamond. It’s a well cut diamond for light performance. Go for that stone.

  11. Tomas-
    January 15, 2018 at 8:55 am


    It seems Blue Nile no longer offers their signature diamonds and introduced Astor by Blue Nile™ diamonds instead. Would you recommend buying those? Seeing as GCAL report is no longer there, would it still be possible to select a good diamond based solely on GemEx certificate they provide instead?

  12. Paul Gian-
    January 15, 2018 at 1:18 pm

    Thomas, you are right. BlueNile rebranded their signature diamonds and have since labeled them as Astor. Effectively, it’s still the same signature diamonds but they have a different name now. They stopped working with GCAL as they felt that the light performance images there wasn’t a true measurement of light reaction from the diamond.

    Instead, they utilize GemEx as it provides a way for Blue Nile to compare all the facet interactions with each other and the quality of the diamond structure itself. Doing so gave two certificates that complemented each other rather than saying the same thing twice. GemEx also provides a visual performance with images on three levels for the customer to see.

    The bottomline is, the video they provide is still the most important piece of information to assess cut quality. Even without the GCAL or GemEx reports, the video of the diamond in neutral lighting is sufficient for an educated decision if you have sufficient experience with diamonds.

    I understand that not all readers may have the same level of experience in eyeballing diamonds for cut quality. If you need help to pick out a stone from the Astor signature line or need me to help you review the Astor diamonds, let me know via email. I would be glad to offer my assistance.

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