I just happen to see your inquirey.
Could you find an example of the lettering or engraving style that did not belong to this other person and post that insted?
You call it "prismatic" would Gothic be more acurate? If that is the case I might hazard a guess, sight un-seen, that what you are looking at was done on a "trophy machine"
This is a set of pantogragh arms that follow the type masters and scribe the copy with a non-rotating diamond point tool. It can be a very nice effect but it is used for lines only. Some of the fancier lettering styles will incude a fill-in lining effect on the thicker parts of letters to give a more finished look, also very nice.