I don't want to rain on your parade nor denigrate those lovely hammers but they were almost certainly forged or cast and then finished by hand, as Steve says above. The engraving is lovely but at that time the number of engravers to the trade who could have duplicated that pattern, to that level of finish, was huge. It was just a matter of how much the customer was prepared to shell out for his new toy. In our era of automated mass production techniques, we forget that nearly everything was built and finished by hand and any level of finish could be bought for a few shillings (shilling=12 old pennies=5 new pennies=$0.07).
If you examine most nice Joseph Lang guns of the period, you will see engraving that will blow your mind on a gun that is really not that special under the skin.
Likewise, the late C19th William Evans guns, built by Webley on the screw grip patent often have the most amazing engraving.
It is a common practise then to finish a fairly commonplace gun very highly so it would command a premium price for a medium quality gun. I'm sure you could find parallels today.
In a way, it is why some very high quality guns are rather understated in their adornment.
