Rarest among all the trademarks that they ever used only because that trademark lasted for the least amount of time. I don't like talking much about trademarks anymore, but I think here I'll make an exception. Partly because the vast majority of drummers wouldn't be able to identify one of these even with an example trademark to go by; so I really don't feel like I'm giving away any timeline secrets by showing you this example.
Most know about "transitional stamps" and what that trademark looks like. If you watch cymbals on eBay you've heard them mentioned now and then. They are fairly rare and highly sought after because most drummers know that they were hand 100% hammered, and so they have that old school character to them. But very few if any know anything about the 1954 era, when cymbals that were virtually the same as the earlier trans stamps were being made but without a version of the trademark that could be as easily recognized as unique. In fact these cymbals are easily confused with early 1960's cymbals.
[img]http://photos.imageevent.com/drumaholic/constantinople/25.2.jpg[/img]
[color=blue]Avedis 25-1/2" 1954 era[/color]
....with multiple trademark stamps. At least 4 tries were made, none of them very successful.
[img]http://photos.imageevent.com/drumaholic/constantinople/Redunderlined.jpg[/img]
At least 2 and maybe 3 were the 1954 trademark, and there's also a partial stamping of the type I large stamp trademark in here as well. Both the 1954 stamp and the type I large stamp are closely related in era, this example apparently shows that they available contemporaneously.