In the case of this 28" cymbal I will concede that what we have here is what was described earlier by Brian. This is a 1950's creation that was sold in the 1980's.
If you watch all the way to the end you'll see a lot of valuable information that led me to this conclusion. First the hollow sold stamped logo is indicative of late 1970's to early 1980's. The trademark is either an original from when it was made or it could be one from the 1980's, its not clear which exactly is the case. The full overview of the cymbal is where the 1950's characteristic can been seen. There are several rows of widely spaced hammering on the top-side, which is an indicator of something very commonly seen in the period of about 1955-1961 but not later. If this cymbal retains the original trademark from back then, it would have to be very early 1960's. The modern trademark from the 1980's is tough to distinguish from that one. But if it was trademark stamped later, then this is more likely to originally be 1950's vintage.
When he turns it over you'll also notice the unique ink stamping there. It has from left to right:
The diameter in centimeters followed by the Avedis Zildjian & Sons written in Arabic script followed by the diameter in inches. This type of ink stamp was applied only on Zildjians sold in Europe.
So in this case as least I will readily concede that this is a much older cymbal that was sold decades later with trademark stamp (old or new) and contemporary ink markings.