Osmium, when combined with boron alone, or in combination with rhenium, ruthenium or iron, produces compounds that are ultra-hard and incompressible. These osmium diboride compounds are useful as a substitute to for other super or ultra-hard materials that are used in cutting tools and as abrasives. The osmium diboride compounds have the formula Os.sub.xM.sub.1-xB.sub.2 where M is rhenium, ruthenium or iron and x is from 0.01 to 1, except when x is not 1 and M is rhenium, x is from 0.01 to 0.3.