As far as the dates go, the Istanbul cymbals from the 80's had green ink stamps. In the early 90's, the changed to black ink stamps. So yours is from the 90's.
I wasn't going to go into more detail, but just some small amendments for future readers...
Actually, the earliest ones had ink logos which seemed to be "crudely" spray painted in black and did say Zildjiler. Those were replaced quickly because of a threatened lawsuit from company called Zildjian (you may have heard of them) who claimed it was "too close" to their name. The die stamp stayed Zildjiler (which is the registered company name in Turkey) but the ink changed to Istanbul. Again the earlier ones were "crudely" spray painted black (as if the mask wasn't held tightly against the cymbal leading to slight overspray). Sorry I can't show a picture, but if you've seen one you'll know what I mean. An unknown time later the ink labels started looking like your usual silkscreened ink we know see on this one.
Alas, as more data comes to light, the black and green ink labels seem to coexist in time. Last I heard (not that I pay super close attention) the color was no longer a "safe" way to estimate age. And nobody has any evidence supported theory about why some are green and some are black. At least, if they have such a theory then news hasn't reached my ears. Like most things, I started paying close attention when I had a presplit, and haven't kept up since I moved it on. I do still have a nice Agop Istanbul in my collection.
Given that, I'd say it's safer to not distinguish between green and black "periods" and I'd just leave the probable date range as late 80s through 90s. Also so far as I know there aren't any die stamp changes documented. People haven't felt the need to look at these Istanbuls through the microscope as far as dating them goes. They are nice. You play them. Simple.
There were USA distributor problems (can't remember the year) and hundreds of these were dumped on the market at very low prices. Perhaps a liquidation of existing stock from the outgoing distributor. This one may have been picked up then for a low price (with hindsight I wish I had purchased some then).
Enjoy.