Since it has ZILDJIAN ink rather than a K, I presume it is an A Zildjian. You cut off the diagnostic part of the trademark stamp. But the hammering and lathing looks consistent with a 1980s A Zildjian. That production era also marked the beginning of the Avedis Zildjian company producing K Zildjian cymbals at their USA plant. There are a few cymbals from the early 80s period which don't fit the simple A vs K categories, as they have say K hammering but an A Zildjian trademark stamp, or vice versa. It was a period of change and sometimes the worker just put the stamp (ink or trademark) on uʍop ǝpᴉsdn. If you have a close look at the trademark and it says K Zildjian rather than A Zildjian let us know. I'd also be interested to know the weight. I collect weight information particularly for cymbals which have model or weight class ink.