Type IIa Diamonds: The Best of the Best

When learning and reading about diamonds, the term “Type IIa” occasionally arises. These Type IIa diamonds, unanimously dubbed the best of the best, are incredibly rare due to their rigorous classification guides and unique chemical makeup. They make less than 1% of the world’s diamond output! Owning one has been compared to “owning a Rembrandt” (Robb Report, 1997). But what exactly is a Type IIa diamond? It is much more than meets the eye. Today we will delve into what makes Type IIa diamonds so special and where they can be found.


Christina Onassis’ 38.00 Carat Type IIa Diamond necklace by Harry Winston


Christina Onassis’ 38.00 Carat Type IIa Diamond necklace by Harry Winston

Golconda Diamond Drop Earrings, 14.31 Carats

Golconda Diamond Drop Earrings, 14.31 Carats

What is a Type IIa diamond?

Diamonds are scientifically classified, analyzed and then organized according to their color and other physical properties. This study differentiates between natural, lab-grown and treated diamonds. The most typical kind of diamond is a Type I diamond, which contains nitrogen as an impurity. Type II diamonds do not have nitrogen, making them significantly more pure. From here, the two types are classified as Type Ia, Type Ib, Type IIa and Type IIb.
Type IIa diamonds are notable for their absence of nitrogen or boron, the main components that cause impurities and unwanted colors in diamonds. They are the most technically pure diamonds in the world and are exceptionally rare because of this. Without the impurities, these diamonds are able to transmit UV rays and visible light that other diamonds block, making them superbly beautiful to the eye.
For some context, describing the color of a white diamond involves an alphabetized system. White diamonds are often referred to as the letter grade they were assigned during diamond certification, the D to Z color grading scale. They are also sometimes described with the degree of how colorless the stone is. These descriptions directly correlate to the color grade that the stone may have:

    • Colorless (D, E F)
    • Near Colorless (G, H, I J)
    • Faint (K, L M)
    • Very Light (N, O, P, Q, R)
    • Light (S, T U, V, W, X, Y, Z)
The whitest non-Type IIa diamond would be rated at a “D” color, whereas Type IIa diamonds appear two shades lighter — a rank not even specified in the typical alphabetized color ranking.

Golconda Diamond Drop Earrings, 14.31 Carats
Harry Winston 5.56 carat Type IIa Diamond Ring

What is a Golconda diamond?

Type IIa diamonds are sometimes called Golconda diamonds, though not all technically are. This nickname arose in reference to the incredible gemstones that were found in the Golconda region of India in the 16th and 17th centuries. This area of India is known as the Godavari Delta in modern-day Hyderabad. Diamonds were harvested at these mines for over 2000 years and were the only source of diamonds until the 17th century. Colloquially, however, Type IIa diamonds and Golconda diamonds are synonymous. The phrase “Golconda diamond” invokes the spectacular and rare nature of the Type IIa diamond.

Where can Type IIa diamonds be found?

While we know that Type IIa diamonds were once found in the Indian Golconda mines, today they can be found in many other locations worldwide. Type IIa diamonds only need to meet the set guidelines to be classified as such.


Finding Type IIa diamonds on the market is incredibly rare. In fact, Type IIa diamonds are so rare that most jewelers and gemologists will spend their entire careers without seeing one in person. Golconda and Type IIa diamonds are so highly coveted that they sell quickly and with a significant premium. We currently have a great selection of Type IIa or Golconda diamonds.


Golconda diamond ring, 3.18 carats


Golconda diamond ring, 3.18 carats

What makes Type IIa the greatest diamonds?

These diamonds are so sought after because of their beauty and rarity. Stars like Elizabeth Taylor and Christina Onassis wore these superb gemstones. Additionally, Golconda diamonds will sell for 25% to 30% more at auction than a D-colored counterpart. They are widely regarded as the perfect stone.


Some of the world’s most famous diamonds are actually Type IIa diamonds. The Hope Diamond, the Cullinan, the Koh-I-Noor, the Darya-I-Noor, the Winston Legacy and the Star of the South are all examples of the superb Type IIa diamond classification. These diamonds can be found in royal gem collections and museums around the world.


Pear-cut Golconda diamond ring, 3.02 carats

Pear-cut Golconda diamond ring, 3.02 carats

How can you tell if a diamond is a Type IIa?

Diamond grading services like the Gemological Institute of America (GIA) or the American Gemological Lab (AGL) can determine if a diamond is a Type IIa or not. Labs like this are the only way to determine if a diamond is truly boron, nitrogen and inclusion free. Though Type IIa diamonds look spectacular to the eye, they must be certified before receiving this classification.

How do I know when new Type IIa diamonds are available at M.S. Rau?

Since we are always receiving new jewelry inventory, you can stay up to date by checking out our website or signing up for emails. Because we love to find the best of the best, we are always looking for jewelry designs featuring Type IIa diamonds to share with you.


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