Apart from subtle variations in design, stamps that are printed from different plates, on paper with different watermarks (a faint design in the paper, visible when held against the light), and even those with a different number of perforations (the holes along the edges) all command the interest of specialized collectors.
एक डाक - घर कर्मचारी को जालसाज़ी किए जाने का संदेह होता यदि उसके द्वारा निपटाए गए अनेक पत्रों पर टिकट के दोनों अक्षर समान हों ।