Normally, one checks for Watermark first.
This one unwatermarked, so check for confirmation of Engraving
(They say smooth some kitchen tin foil over the face to see an impression)
Locate the Catalogue number, then search
ebay for similar stamps
to see if your example remotely matches.
ebay $270
Seek Google links for Forgery ID on Tasmanian stamps
Supply a clear, up close and personal image here (600dpi)
Good Luck.