Sold in the 1920s as nearly diamond
When cemented tungsten carbide reached the market in Germany in the 1920s, it was sold under a name meaning 'like diamond'. It is not quite that hard, but it sits close to sapphire on the hardness scale and far above steel. That is why the small red knife sharpener from Pakistan on this page can raise a fresh edge on a steel blade in a few strokes.
