The years for the stamps in the 1950s aren't known exactly, and neither are the boundaries between the decades defined exactly. There are at least 4 identified Transitional Stamps and they span the later half of the 40s through the early 50s. As Mike says all the Trans Stamps share the feature of not having dots in the U S A (among other things).
Then you have 3 Large stamps from the mid 1950s.
Then you have 2 Small stamps from the late 1950s, although once again we don't know exactly when the factory stopped using the Small Stamp dies and started using what we call the 60s dies. You can be fairly sure it wasn't December 31, 1959 or January 1, 1960. There are two identified Small stamp dies, and the one on your cymbal is thought to be the earlier of the two (called SSA) based on the top portion being incompletely pressed in. That is a proxy for measuring the width of the Zildjian Co accurately. The SSA version is maybe 1957ish, 1958ish. But I prefer to just say "late 50s" because we really don't know the years that accurately.
Your 18" is tied for lightest with one I have in my database for that production era. This was the graph a year ago.
[img]http://black.net.nz/avedis/images/A18-weights-by-era.png[/img]
As of today, there are 6 sub 1120g cymbals which include
[LIST]
[*]A Zildjian & Cie Vintage crash (these were targeting Trans Stamps so that's not a suprise)
[*]Two Large Stamps
[*]One Trans Stamp
[*]One 78-82 Crash (probably a Paper Thin but the model ink is gone)
[*]One SSB (at 1115g it is slightly lighter than yours).
[/LIST]
This is out of 305 18" Avedis Zildjian cymbals I've got weights for (excluding Swish models which tend to be light). So yours is in the lightest 2%. Nice find.
The Joe Morello Take 5 ride also has an SSA stamp (same as yours) and my information says Take 5 was recorded on July 1, 1959 for the Time Out album. This fits with it being a fairly new cymbal at the time. Where does your year for the recording come from?
