The ornamental design for decorative glass, as shown and described.
FIG. 1 is an isometric view of an embodiment of a decorative glass showing the upper and lower edges of the decorative band in solid lines and the portions between the upper and lower edges of the decorative band shown in phantom and form no part of the claimed design;
FIG. 2 is a front elevational view of FIG. 1;
FIG. 3 is a top plan view of FIG. 1;
FIG. 4 is a bottom plan view of FIG. 1;
FIG. 5 is an isometric view of another embodiment of a decorative glass showing the upper and lower edges of the decorative band in solid lines and the portions between the upper and lower edges of the decorative band shown in phantom and form no part of the claimed design.