Die numbers for SG57;
1 through 5
(WW1, 2WW, 3WW, 4WW or 5WW are embossed at the base of the neck)
Die 5 is extremely rare
The WW stands for William Wyon, the engraver. These letters and numbers can be faint or even invisible.
The die for the embossed stamps was engraved by William Wyon, and based on his Wyon City Medal of 1834 which depicted a fifteen-year-old Victoria
A 1901 essay of a telegraph stamp of the same design