Virtual Purchase: 1 Carat Round Diamond

Several times a month, I am going to do a “virtual purchase” of a piece of jewelry.  I will  articulate a jewelry purchase scenario, and go through the decision-making process of what, how and where I choose to “purchase” the item.

What:  This week I am looking for a 1.00 carat round diamond, loose.  My “customer” wants the nicest quality he can afford, but won’t go below 1.00 carat weight.  I am only going to look at diamonds with an AGS or GIA certificate so there is some confidence that I will get the diamond quality I’m expecting. 

Where: I am going to shop online at Blue Nile,,, and Union Diamond.

(The Gold Standard) Blue Nile:  I go to Blue Nile first.  I do a search for loose diamonds that can be mounted by a specific date (if you are more flexible on date, there are more results), 0.90 to 1.15 carat, Very Good Cut or better, I Color or better, SI2 Clarity or better.  There are 246 diamonds in my search result.  Now it’s time to refine.   I review this primer on diamond quality 4 Cs, so I know that cut is important.  I sort for that and find that only 2 of the 215 diamonds are Very Good Cut, the rest are Ideal or Signature Ideal.

I know that color is also important, so I sort for that next, high to low.  I decide that a D or E color, while beautiful, are much more expensive than the equally gorgeous F and G color, and that VS2 to SI1 clarity seems like a nice range.  So I check the compare boxes next to a few combinations of F and G color, VS2 and SI1 clarity, Very Good, Ideal and Signature Ideal cut, and hit the “Compare” button at the top of the column.  It opens a new page with the diamonds listed side-by-side in a neat comparison format. 

I remove 3 diamonds right off the bat, due to medium to strong blue Fluorescence.  It doesn’t really affect beauty that much in faint to medium (and may make the diamond more attractively priced), but while it might actually help me out if I were purchasing an I or J (or lower) color, in a premium color diamond, it’s not that desirable.  The diamonds that are left range from $5300 to $8800–kind of a big price spread.  I rule out the 2 highest priced diamonds (over $8000), mainly because there is nothing significantly better about them than the others.  Wearing my Gemologist hat, I scrutinize the numbers for a while.  I ultimately choose a 1.09 ct F, SI1, Signature Ideal for $6783.  What tips me this direction is that it has a 60% depth percentage with a 56% table, so its diameter is going to appear slightly larger than the other top contender at 62% depth/55% table.  The actual diameter measurement is also slightly larger, but I know I’m not sacrificing beauty for that, because it’s a Signature Ideal cut with the certificates to show for it.  It wasn’t the cheapest, but it was right in the middle of the pack ($5300 low to $7600 high).

(The Mighty) Now that I have a more precise picture of what I’m looking for, I head to (is there anything they don’t sell now?).  As an insider (see here to read more), I know that Amazon tries to be the lowest price in loose diamonds whenever they can.  At Amazon’s site, you can find their loose diamond/Create Your Own Diamond Ring selection on their Jewelry gateway page, or by clicking here

I adjust the sliders to find diamonds in the same quality range I used for Blue Nile, with a price cap of $10,000.  I figure out (through trial and error) that Amazon’s slider is not as sensitive as Blue Nile’s so I have to move the slider up to 1.25 ct in order to get diamonds over 1.00.  I get 631 results.  Their compare feature does not have the same level of detail as BN’s–there are no measurements or girdle thickness, you have to click through to the detail page for each stone to find out those details.

I found a great 1.08 F, SI1 “Ideal” cut (meaning that the table and depth percentages fit into the Ideal range), that looked like a great value at $5775.  But closer inspection revealed that it said “Very Good” under the Polish and Symmetry comments, so it’s not technically the same as the Signature Cut Ideal from Blue Nile.  But if you weren’t so picky about that, it would be a great value.  Since the G, VS2 combination was $1000 more, I stuck with the F, SI1 quality combination.  The final diamond at Amazon that is most comparable to the BN diamond is a 1.07 ct F, SI1, Ideal cut for $6610.  I like the 55% table/61% depth combination, and it’s diameter is 6.6 mm, similar to the BN diameter of 6.7 mm.  If I wanted about the same factors, but was willing to go down in size slightly to 1.00 ct exactly, Amazon had a nice diamond for $5940, but the diameter is slightly smaller at 6.46 mm.   

(Disappointing)  I couldn’t find a great comp at  The closest I could find was a 1.03 ct, F, SI1, Ideal cut for $5908.  It is not as large, and had medium blue Fluorescence, which I rejected at the other companies.  The selection was dismal, maybe 4 diamonds that were even close.

(The Darkhorse Surprise) Union Diamond: Union Diamond seems to come up a lot in search engines, so I checked them out, too.  Closest comparable diamond: a very nice 1.06 ct, F, SI1, AGS-certified Ideal cut for $6435.  If it is as nice as the website says, it’s one of the best values I came across, especially if the company could verify if the AGS certificate identifies the diamond as a “000” Ideal (Ideal proportions, Polish and Symmetry).  The only drawback is that I’m not as familiar with the company, so I can’t give a full endorsement without ordering something.

Final Diamond Virtual Purchase:the 1.07 ct F, SI1, Ideal from  While any of my top three diamonds (my top pick from BN, and Union) would have been incredibly brilliant, I like the value proposition of the price in the middle ($6435 from Union Diamond, $6610 from Amazon, $6783 from BN), PLUS the safety/reputation of  If I get some personal experience with Union, or hear from someone who has, then I might go with that option.

Bottom Line:  With certified diamonds, you can–in theory–easily compare all the factors online and then buy something that should be a beautiful diamond.  The reality is that it’s pretty confusing trying to sort through literally hundreds, even thousands of similar diamonds that all have tiny differences that seem to affect value significantly.  It’s important to remember that although it seems like there are so many details to consider, at some point it’s splitting hairs–if you are staying in a quality range of Very Good Cut, I color, SI2 and better, you will end up with a gem with plenty of sparkle.  I chose an Ideal, F color, SI1 as a gorgeous diamond quality with an excellent value proposition.  A lot of people think that a G, VS2 combination is an ideal engagement ring, but most of those diamonds were $1000 or more for that quality combo, and I prefer the higher color–you can’t see the difference in clarity at all from VS2 to SI1.

Of course, if you go to a reputable jeweler in your area, you could compare several qualities and see for yourself if there is a difference worth paying for.

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