Characterizing is merely describing what an object looks like or appears to be, which isn't that hard. Describe its shape, color, if there are any writing or embroidery (stitch work/needlework) on it, its texture (how it feels), how it reacts to environments, etc.
If you meant categorizing objects. Characterize (if that is even a word) the object like above and link those characteristics to similar shapes, and you have a category.