The world's largest black diamond

The Enigma is a black (carbonado) diamond and is the world's largest cut diamond, according to the Guinness World Records, weighing 555.55 carats (111 grams) with 55 facets.

Aside from its unusual color and unique shape, one of the most unique features of the Enigma is that it may have come from outer space. According to Sotheby's, the Enigma was either created by a meteorite impact or came from an asteroid colliding with Earth. However, black diamond experts are not sure about this.

Black diamonds have a high concentration of opaque minerals, especially graphite, a dark gray form of carbon with a hexagonal structure, and metal sulfides, according to Peter Heaney, a professor of geological sciences at the University of Pennsylvania. Sotheby's describes Enigma as a carbonado diamond. However, not all black diamonds are carbonado. Instead, carbonados are a type of black diamond that is both polycrystalline and porous. Carbonado diamonds also contain uranium-rich phosphates, which create a halo of radiation around the pores on their surfaces. That makes them highly absorbent of white light, completely opaque, and much darker than other types of black diamonds.

Carbonado is extremely hard and durable due to its polycrystalline and porous nature. This makes it perfect for industrial applications, such as oil drills used to penetrate hard volcanic rock. Judging by its size, it is likely that the Enigma is indeed carbonado, but it is difficult to be certain because the diamond has been cut.

All known carbonado diamonds have been found in Brazil or the Central African Republic, dating back 2.6 to 3.8 billion years. During that time, the two countries were part of the same supercontinent called Rodinia. Scientists have discovered black diamonds from meteorite impacts in the past, but they were usually very small. "I would be very surprised if a diamond as large as Enigma came from a meteorite impact," Heaney said.

Other theories have speculated that carbonado diamonds could have been found in asteroids that crashed into Earth or formed in powerful stellar explosions called supernovae, but there’s not enough evidence to support that. Instead, Heaney suggests that carbonados originated on Earth. However, the exact mechanism by which black diamonds are formed is unknown. Most diamonds form when high pressures in the Earth’s mantle squeeze out organic carbon. But the oldest carbonado diamonds may predate life on Earth, so researchers aren’t sure they formed that way.

An Khang (According to IFL Science/Live Science )

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