A method of marking a sintered body includes the step of preparing the sintered body by sintering a mixture of first and second types of powder particles. The first type of powder particles is made of a first material and the second type of powder particles is made of a second material that has a different etch susceptibility from the first material. The method further includes the step of writing ID information on the surface of the sintered body by forming a first concave region to a depth of at least about 10 nm under the surface of the sintered body and a second concave region under the first concave region, respectively. The first concave region is formed by etching away both the first and second types of powder particles, while the second concave region is formed by etching away only the first type of powder particles.