<p>Disclosed is a ruby glass which can develop a good red color (so-called a copper ruby color) stably without the need of carrying out a re-heating treatment. The glass contains Cu in an amount of 0.025 to 0.85 mol% in terms of a Cu2O content and S in an amount of 0.023 to 0.078 mol% in terms of a SO3 content, wherein the ratio of the amount of Cu and the amount of S is 1.50 to 0.70 in terms of a [(molar amount of Cu in terms of a Cu2O content)/(molar amount of S in terms of a SO3 content)]. It becomes possible to produce a ruby glass which can develop a color stably.</p>
