Need help with Diode ID

[tom_]

I have two diodes in front of me but being absolutely new to electronics I have no idea which is what.

One is a 1N4742 Zener Diode, the other is a 1N4148 diode.

I have no idea which one is the Zener as they look similar. The only difference is the size. One is about half the size of the other.

[pebe]

The datasheet for the 1N4148 gives its dimensions as: Length = 3.9mm, Diameter = 1.9mm.
Hope that helps.

[yy482]

you can search the data sheets from datasheetcatalog.com for the detail