Often described as “purest of the pure”, Type IIa diamonds make up only 1-2% of all natural, gem-quality diamonds. Considering its excellent quality and mineral source that is almost exhausted, this makes Type IIa highly prized and coveted.
Diamonds are measured at the atomic level and this requires using an infrared spectrometer to detect. Depending on the amount of nitrogen impurities each has, there are four types of diamonds: Type Ia, Type Ib, Type IIa and Type IIb. Type I diamonds will usually contain traces of nitrogen and make up to 98% of gem-quality diamonds.
Type II diamonds are classified as diamonds with extremely low nitrogen content, which cannot be measured by existing instruments. As for Type IIa diamonds, it is completely nitrogen-free and often appears colorless.
Because Type IIa diamonds contain almost no nitrogen, it is magnificently pure. Compared to Type I diamonds, it is more transparent and light, so it is often likened to a pool of crystal clear spring water, or a solidified bead. Some people call this diamond color “Super D”. The fascinating part about this type of diamond is beside its blazing fire light, there is also quiet and pure water light that is just as hypnotic.
Usually Type IIa is a colorless diamond, but there are also a small number of yellow, brown, orange, pink, red or purple color to the gem. As Type II diamonds are formed under extremely high pressure for longer periods of time, the crystals found tend to be larger and irregular in shape as well. Iconic large diamonds, such as the Elizabeth Taylor Diamond, Koh-i-Noor or Cullinan— previously the largest diamond in the world—are all Type IIa diamonds. These natural diamonds are highly valued for their naturally large carat weights. In recent years, Sotheby’s auction has seen a astounding pieces such as a 49.31 carat Type IIa oval, brownish-yellow diamond, as well as a 15.38 carat Type IIa pink diamond.
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