Superhard materials

Sapphire is a gemstone variety of the mineral corundum, an aluminium oxide (α-Al2O3).

Graphene (/ˈɡræf.iːn/) is an allotrope of carbon in the form of a two-dimensional, atomic-scale, honey-comb lattice in which one atom forms each vertex.

Corundum is a crystalline form of aluminium oxide (Al2O3) typically containing traces of iron, titanium, vanadium and chromium.

Niobium carbide (NbC and Nb2C) is an extremely hard refractory ceramic material, commercially used in tool bits for cutting tools.

Zirconium nitride (ZrN) is an inorganic compound used in a variety of ways due to its properties.

Cemented carbide is a hard material used extensively in cutting tools for machining, as well as other industrial applications.

Zirconium carbide (ZrC) is an extremely hard refractory ceramic material, commercially used in tool bits for cutting tools.

Chromium carbide is a ceramic compound that exists in several different chemical compositions: Cr3C2, Cr7C3,and Cr23C6.

Beryllium carbide, or Be2C, is a metal carbide.

Lonsdaleite (named in honour of Kathleen Lonsdale), also called hexagonal diamond in reference to the crystal structure, is an allotrope of carbon with a hexagonal lattice.

Silicon carbide (SiC), also known as carborundum /kɑːrbəˈrʌndəm/, is a compound of silicon and carbon with chemical formula SiC.

Boron carbide (chemical formula approximately B4C) is an extremely hard boron–carbon ceramic, and covalent material used in tank armor, bulletproof vests, engine sabotage powders,as well as numerous industrial applications.

Titanium carbide, TiC, is an extremely hard (Mohs 9–9.5) refractory ceramic material, similar to tungsten carbide.

Vanadium carbide is the inorganic compound with the formula VC.

Tungsten carbide (chemical formula: WC) is a chemical compound (specifically, a carbide) containing equal parts of tungsten and carbon atoms.

Rhenium diboride (ReB2) is a synthetic superhard material.

Tantalum carbides form a family of binary chemical compounds of tantalum and carbon with the empirical formula TaCx, where x usually varies between 0.

A ruby is a pink to blood-red colored gemstone, a variety of the mineral corundum (aluminium oxide).

Iron tetraboride (FeB4) is a superhard superconductor consisting of iron and boron.

Zirconium dioxide (ZrO2), sometimes known as zirconia (not to be confused with zircon), is a white crystalline oxide of zirconium.

Yogo sapphires are a variety of corundum found only in Yogo Gulch, part of the Little Belt Mountains in Judith Basin County, Montana, United States, on land once inhabited by the Piegan Blackfeet people.

Boron nitride is a heat- and chemically resistant refractory compound of boron and nitrogen with the chemical formula BN.

Silicon nitride is a chemical compound of the elements silicon and nitrogen, with the formula Si3N4.

Titanium nitride (TiN) (sometimes known as tinite) is an extremely hard ceramic material, often used as a coating on titanium alloys, steel, carbide, and aluminium components to improve the substrate's surface properties.

Stishovite is an extremely hard, dense tetragonal form (polymorph) of silicon dioxide.

Diamond is the allotrope of carbon in which the carbon atoms are arranged in the specific type of cubic lattice called diamond cubic.