For as long as I can remember in my 45+ years in the diamond and jewelry business, the most sought after diamonds in terms of GIA color and clarity grading has been “SI” (Slightly Included) quality diamonds. The reason for this is simply that a “nice” “SI1” or “SI2” clarity grade diamond often represents the best value in terms of the diamond’s appearance in relation to its price.

There are several caveats to this statement. Most importantly it is imperative when buying any diamond to buy a diamond that is graded by the GIA (Gemological Association of America). A GIA grading report (also referred to as a GIA Certificate) is the only diamond grading laboratory that is trusted and respected. All other diamond grading laboratories are BS! Yes, you read that right! The GIA is the ONLY diamond grading authority that is meaningful and accepted by those who are knowledgeable and respected in the diamond trade.

The SI (Slightly Imperfect) clarity grade is defined by the GIA as diamonds that contain “minor inclusions somewhat easy to see under 10x magnification” by a trained diamond grader in laboratory conditions. The “SI” clarity grade accounts for the majority of diamonds that are graded by the GIA.

“SI1” and “SI2” graded diamonds are the heart and soul of the diamond business. These are the most sought after grades in the industry by diamond dealers and traders as well as knowledgeable buyers. “SI” grade diamonds also represent the widest range of diamond quality within any diamond grade with regard to pricing and appearance. A “SI” graded diamond can be spectacularly beautiful or not beautiful at all – in other words “Ugly”!

Honestly, most “SI” graded diamonds are ugly. They contain inclusions that are visible to the eye without magnification. They may contain large black inclusions. They may contain multiple inclusions. They may have large ‘blob” like inclusions. They may have have “milky” or “dead” appearance because of the inclusions.

On the other hand, a diamond with a “SI” grade may be as beautiful and as brilliant and as “clean” as a Flawless diamond. This is indeed the rare “SI” graded diamond but this is what makes a diamond merchant’s life challenging . . finding that “SI” graded diamond that is exceptional because it represents the perfect “sweet-spot” of all diamonds. When found, it represents the perfect balance of diamond size and beauty and price!

The difference in price between exceptional “SI” graded diamonds and the other “SI” graded diamonds is significant. A beautiful “SI” graded diamond may be 50% or more expensive than an ugly “SI” graded diamond. Despite the “high” price of the top “SI” grade diamonds, this diamond will usually be priced significantly less than a “VS” grade diamond and will, in many cases, be as beautiful or perhaps more beautiful than a “VS” grade diamond.

The most important advice when buying a “SI” graded diamond is this: It is necessary to look at the diamond and not simply the diamond grading (GIA) report. After all, it is a diamond you should be buying and not a grading report!

For purposes of educating the consumer on the differences between “SI” graded diamonds, I will attempt to illustrate the differences by using images of actual diamonds and the corresponding GIA reports:

When looking at the diamonds in the photos above, it should be obvious to the reader that a GIA clarity grade is not the “tell all” when evaluating a diamond. This is true is all diamond grades with the exception of the “Flawless” grade. It is most noteworthy when evaluating diamonds in the “SI” range since, as previously stated, the “SI” grades have the largest ranges of appearances of all GIA clarity grades.

The diamonds in the top two photos are “UGLY” diamonds. These two diamonds contain large black carbon inclusions that will be obvious to the naked (non-magnified) and untrained eye. This is the reason that these two diamonds are priced at approximately 50% less than the other diamonds that are pictured.

To many people in the trade – and to most diamond buyers, the top two diamonds are not sale-able diamonds. Because of significantly low level of demand for these “ugly” diamonds, prices for these diamonds are very low in comparison to the other diamonds. In the world of diamonds, these ugly diamonds will get sold. They will be sold by unscrupulous diamond sellers who, like some consumers, believe that low price is all that matters! Also, these diamonds are sold by unscrupulous diamond sellers because their low price enables the reseller to make larger profits!

These low price ‘ugly” diamonds are also bought by unknowledgeable internet buyers for the reason cited above – they are low price items in relation to the others in online diamond listings and unknowing customers think they have beaten the system by buying a “cheap” diamond online. Such buyers do not understand the difference between low price and “value”.

The “service mark’ of my business – a business that is approaching its 100 year anniversary, is “The Right Diamond at the Right Price”. I mention that here because the top two diamonds above are certainly not the “Right Diamond”. At any price!

The middle diamond pictured above is a more typical GIA graded “SI2” diamond. It contains several inclusions which may or may not be noticeable to the non-magnified or untrained eye. This diamond will still be a nice and brilliant and scintillating diamond when set into a ring. Still, this diamond does contain inclusions that are located in the “table’ (center area) of the diamond which is something that I try to avoid when choosing the “Right” diamond. As you can see, this diamond is considerably more expensive than the the first two diamonds. It is also a much more sought after diamond by knowledgable and trustworthy diamond dealers and by most consumers.

The fourth diamond in the listing above is what I consider to be a “SI2(+)” diamond. The diamond does have several minor inclusions in the table area which some may find objectionable, however this diamond will be eye clean and should have great life and brilliance when set into a ring. It is my opinion that this diamond is certainly worth the 7% price difference of the prior diamond.

The final diamond pictured above is an exceptional “SI2” grade diamond. This diamond will have exceptional brilliance and life in a ring. This diamond will also look clean under magnification. This is a great diamond. It is the exceptional “SI2” grade diamond that a knowledgable diamond dealer looks at and says “Why is this an SI2?”. This is the diamond that I own in my inventory because this is “The Right Diamond at the Right Price”.

Getting back to the title question of this post – whether an “SI” (Slightly Imperfect) grade diamond is the “Right’ or a “Bad” choice when buying a diamond, the answer is “It depends on the diamond”. All diamonds are a unique creation of nature. Each diamond is different. I wouldn’t suggest choosing a wife based on a text description of what she looks like. I would hope that you at least see a photo or a video – but, to be sure, I would hope that you see her and know her before making such an important decision. The same is true about a diamond. It is a big investment in terms of dollars and a commitment hopefully for a lifetime. Be smart about it. A beautiful diamond is something you will look at everyday for many years!

Author’s Note: The diamonds above are shown with a retail price. Retail pricing will vary between different stores and regions and other variables. Prices for similar diamonds may be significantly less or more expensive depending on the reseller. Though these retail prices may differ, the pricing differentials based on qualities as shown above will be similar to those stated above as these prices are all based on actual wholesale costs.

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