Diamond dust

This meteorological phenomenon is also referred to simply as ice crystals and is reported in the METAR code as IC.

Because diamond dust does not always reduce visibility it is often first noticed by the brief flashes caused when the tiny crystals, tumbling through the air, reflect sunlight to the eye.

Artificial diamond dust can form from snow machines which blow ice crystals into the air.

Diamond dust may also be observed immediately downwind from manufacturing facilities or chilled water plants that produce steam.

This combination results in crystals with well defined shapes - usually either hexagonal plates or columns - which, like a prism, can reflect and/or refract light in specific directions.

While diamond dust can be seen in any area of the world that has cold winters, it is most frequent in the interior of Antarctica, where it is common year-round.

[3] Note that images are different from the naked eye in that they capture out-of-focus crystals which are shown as large, blurred objects.

Falling diamond dust (Inari, Finland)
Halo display at the South Pole (1980), featuring a parhelion , 22° halo , parhelic circle , upper tangent arc and Parry arc . Diamond dust is visible as point-like reflections of individual crystals close to the camera.
Diamond dust in Løkken Verk , Norway.