Watermark Check - The rotary press, perf 10 coil stamp must be checked for watermark. The flat plate stamp must be single-line watermarked, the rotary stamps may be either.
|Printing Method||Coil Type||Watermark||Number|
|Flat Plate||perf 10 vertically||single-line||446|
|Rotary Press||perf 10 vertically||single-line||457|
|Rotary Press||perf 10 vertically||none||495|
The 4¢ flat plate perf 10 coil stamp, Number 446, is an unlikely candidate for unused fakes, although fakes do exist. Pay particular attention to stamps with a guide-line at top or bottom. These are often trimmed copies of the normal sheet stamp, Number 427, with the guideline along a natural straight-edge and the opposing side trimmed. The incentive for fakery is much greater here, since straight-edge stamps are not as desirable as their fully perforated counterparts.
The addition of a guide-line to a pair is often seen, since guide-line pairs are so valuable. On the other hand, if the (vertical) guide-line passes the "engraved" test, the coil pair is almost certainly authentic, since there is no single-line watermarked imperforate stamp from which to create these fakes.
It is quite likely that the used stamp could be a trimmed fake of the sheet stamp, Number 427. These will not measure up however. The flat plate coil should measure close to 25.0mm from edge to edge. This is not a hard and fast rule, but coils that measure less than the desired measurements should be carefully scrutinized. There is a high likelihood that anything more than a millimeter off is a trimmed copy of the sheet stamp.