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.
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.- 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)

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.
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.