titanium dioxide

In 2008, researchers at Hewlett-Packard developed the first practical memristor, using titanium dioxide.

Physical formulas use minerals—typically zinc or titanium dioxide—to create a physical barrier against the sun’s rays, while the latter use chemicals such as oxybenzone, avobenzone, octinoxate and homosalate to absorb UV light.

The pellets are, as before, coated in titanium dioxide and stearin, making them resemble tiny, irregular Tic-Tacs, which can then be mixed with salt.

They aren't diamonds; they're simply well-cut crystals of titanium dioxide.