| abstract |
PROBLEM TO BE SOLVED: To provide a reversible discolorable composition in which the color of an object changes reversibly and immediately according to the type of an external light source and is excellent in quality such as light resistance, and a watch external part using the same. I will provide a. SOLUTION: General formula M 2 O 3 (where M is Ho, Nd Or Pr)), using a reversible discolorable composition having fine particles of one or more rare earth oxides represented by the following formula (1) and a light-transmissive base material in which the fine particles are dispersed. A color changing layer is provided on the upper surface of the dial, etc., which is one of the exterior parts. |