Thread: Engraved Spines

This showed up recently in another thread and I am bringing it up to learn a little more about this process as it relates to straight razors. Some questions: are all razors with 'engraved spines' actually done by someone skilled in engraving? Is this process if done with engraving tools done before heat treating? Is there an approximate time period when makers began engraving the spines of razors?
Any information would be appreciated (and yes, I did use the search box first before posting).
Thanks