Type IIa Diamonds – The Rarest of all Colorless Gems

Diamond prices are largely based upon rarity. The visual differences between clarity grades at the top of the grading scale are negligible –only discernible with a microscope. Yet, you will pay significantly more for a VVS1 than for a VS1 in most cases. The same is true, but to a slightly lesser extent, with color grades. D,E & F are all considered ‘colorless’ and most people have difficulty seeing any difference between them, yet the price for a D color is significantly more than for an F color, all else being equal.
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1.211ct D IF A CUT ABOVE Round Diamond set in Elegant Solitaire Engagement Ring
When we think of ultimate rarity we automatically think of D Flawless diamonds. And indeed they ARE extremely rare. Because diamonds are billions of years old and the journey from 25 miles below the Earth’s crust to the surface is an arduous one, they normally acquire inclusions that affect their clarity, and trace elements such as nitrogen which can affect color. According to AGS Laboratories, over the last ten years only 0. 2% of diamonds submitted for grading were awarded a grade of D IF or D FL. As noted, a D Flawless looks and performs virtually the same as an F VS1, but the price differential can be orders of magnitude higher because of the rarity factor.
*Note: For purposes of this article we will equate Flawless (FL) and Internally Flawless (IF), which only differ by some minor surface blemish.

Cut Quality and Diamond Rarity

Cut quality is a factor that is often not taken into account in discussions about diamond rarity, which is a major oversight in terms of understanding both diamond beauty and diamond value. GIA states that the quality of the cut is the single most important factor determining the beauty of a diamond. And the design, precision and craftsmanship of the cut is entirely determined by man.
So how does cut quality relate to rarity? When the cutter approaches a given piece of diamond rough, he must calculate the eventual yield in terms of market value. Because wholesale market valuation tends to be tied primarily to 3 of the Cs - carat, clarity, and color – cutters almost always target the heaviest marketable finished stone possible (carat is a measure of weight). This approach is at odds with the philosophy of cutting strictly for optimal light performance (beauty). An ideal cut requires sacrificing more of the rough but results in a finished stone with optimized fire and brilliance. Thus, there are exceedingly few superideal cut D Flawless (or D Internally Flawless) diamonds in the market.
A CUT ABOVE Diamonds
Diamonds cut with optimal precision, which are also perfectly colorless and flawless, represent just about the rarest possible quality for diamonds in the normal range (D-Z). Some fancy color diamonds such as vivid pinks and blues are even rarer as evidenced by the astronomical prices that some fetch at auction.

Type IIa Diamonds – the Wild Card for Rarity

There is only one other factor that can make a superideal cut D IF diamond any rarer, and that is a gemological trait known as diamond type. The vast majority of diamonds in the normal range are Type Ia, characterized by some level of nitrogen mixed into the carbon lattice of the diamond at the atomic level. It is nitrogen that imparts the yellow color to diamonds. To the extent that they have more nitrogen, their color becomes more apparent, dropping them progressively through the color grading scale ending at Z. Diamonds with more color than Z fall into the category of fancy color diamonds.
Type IIa diamonds, on the other hand, are almost totally devoid of any impurities. But not all D color diamonds are Type IIa. In fact, a substantial majority of D color diamonds are Type Ia. Only about 1.8% of all gem diamonds are Type IIa. While statistics are not widely available for how many D color diamonds are Type IIa, conservative estimates indicate that less than 1 out of 4 D color diamonds are also in the rarest Type IIa category. According to AGS Laboratories, over the last ten years only 23% of diamonds submitted to the lab that graded D FL or D IF were found to be type IIa.
Type IIa diamonds, due to their purity, exhibit the highest transparency and thermal conductivity of all diamonds. And it is worth noting that it is the nitrogen impurity in the diamond lattice that accounts for not only varying degrees of yellow body color but also fluorescence.
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2.064ct D IF A CUT ABOVE Round Diamond set in Eternity Wrap Diamond Engagement Ring

Type IIa Pricing

As we have seen in terms of rarity, a diamond with ultimate cut, color and clarity (a superideal D IF) is a very rare gem. But when considering pure rarity, a D IF Type IIa takes it to a whole different level. So how does that affect pricing? Since the wholesale price list is predicated mainly on the 3 Cs of carat, color and clarity, diamond type is not figured into the base price. Demand for precision cutting is creating a premium for ideal cut and superideal cut diamonds, and to some extent that can be established quantitatively in the market. Diamond type however, is not nearly as well recognized as a pricing factor.
But it is clear that shoppers interested D IF diamonds are indeed looking for (and willing to pay for) the purity and rarity factor. Clearly, an F VS1 of equivalent cut quality would be just as beautiful and cost much less. So given a choice between a D IF type Ia (most common) and a D IF Type IIa (most rare), it is not difficult to see why more of these buyers would pay a premium for Type IIa. How much a premium is difficult to say, simply because the sample size is so exceedingly small!
But a few things are abundantly clear. An AGS Ideal cut makes a D IF of a given weight much rarer than even a GIA Triple Excellent cut. An ideal cut with proven optical precision is another level above in terms rarity. And a D IF Type IIa is much rarer still. So the ultimate in rarity in diamonds in the normal range is in fact a D IF Super Ideal Type IIa.
Ritani 1RZ7286 Solitaire Engagement Ring
0.705ct D IF A CUT ABOVE Round Diamond set in Ritani 1RZ7286 Solitaire Engagement Ring

Rarity and Rationality

As mentioned at the outset, there is no practical benefit of diamonds at the highest clarity levels, much less what their diamond Type is. Then again, diamonds in general have little practical value - except for the abrasives industry!
Despite that, people all over the world desire diamonds both for their beauty and for their rarity. There are cultural reasons why some people gravitate to diamonds of the highest clarity, and there are personal reasons that individuals desire to own a perfect piece of nature. Combining the most exceedingly rare natural material with the ultimate in diamond craftsmanship brings you to D IF Type IIa Superideal. A diamond simply cannot get any better than this. Or more rare!

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