Aluminum oxide nanoparticles are of great importance. Aluminum oxide is also known as alumina, bauxite or corundum. It is a compound that is found naturally in the earth's surface and has numerous uses in industry; one of them and the main one as raw material for the production of aluminum and industrial ceramics. The properties both physical and chemical of the aluminum oxide can vary depending on its natural form, either crystalline or noncrystalline. In fact, in nature it can be found in reddish, grazed, blue, greenish, gray and translucent colorless shades. Aluminum Oxide crystals are used in the production of ceramics, as a thermal insulator and as an abrasive. The trend is to use it as an inexpensive substitute for diamond for industrial and jewelry uses. Aluminum oxide is also used to protect titanium oxide coatings, a compound which is widely used as a pigment for paints and plastics papers. It also helps to prevent oxidative reactions of these products with the atmosphere. Moreover, aluminum oxide is used for fillers in the welding industry.