I acquired this 18" 1496g cymbal in January 2013. The seller made the following claims about its history: "late 1953 Avedis Zildjian 18 inch crash ride, acquired from a retired drummer who received it as a gift from the late great jazz drummer Shadow Wilson... (stamp was) produced for only a few months late in 1953 right after Zildjian ended its trans-stamp engravings and right before the company began its small engraving in 1954."
I'll let some others here give their opinions on the above dates. I thought this stamp was so different from anything I've seen on the internet so I'm posting detailed photos, along with detailed dimensional data in inches and mm as measured with a digital caliper.
Overall stamp height: 1.916", 48.66mm
Distance from cymbal edge: 2.915", 74.04mm
AVEDIS height: 0.150", 3.81mm
AVEDIS width: 0.792", 20.12mm
ZILDJIAN CO height: 0.174", 4.42mm
ZILDJIAN CO width: 1.536", 39.02mm
Mounting hole diameter: 0.460", 11.69mm