<p>A polishing composition which comprises an abrasive and water is provided. The abrasive comprises zirconium oxide particles. In one embodiment, the crystallite size of the zirconium oxide particles as calculated on the basis of the diffracted X-ray intensity measured in the vicinity of 2? of 28.0° in the powder X-ray diffractometry and that as calculated on the basis of the diffracted X-ray intensity measured in the vicinity of 2? of 31.0° therein are 330 Å or more, while the mean primary particle diameter of the zirconium oxide particles is 0.2µm or more. In another embodiment, the mean secondary particle diameter of the zirconium oxide particles is 1.0µm or less, while the value obtained by dividing the mean secondary particle diameter of the zirconium oxide particles by the mean primary particle diameter thereof is 1.5 or less. The polishing composition is usable in polishing a hard and brittle material such as sapphire.</p>
