How did Colt stamp the different generations of SAA serial numbers?

[what would you say]

This is probably an all too easy question for the SAA enthusiasts but it could come in handy for me when authenticating single actions and just simply curious.
By what method did Colt put the serial number ,on the 1st , 2nd, and now 3rd gen Single Actions, on the revolver?

They obviously look different and more uniform now and more handmade in the earlier generations.

[Rick]

This is probably an all too easy question for the SAA enthusiasts but it could come in handy for me when authenticating single actions and just simply curious.
By what method did Colt put the serial number ,on the 1st , 2nd, and now 3rd gen Single Actions, on the revolver?

They obviously look different and more uniform now and more handmade in the earlier generations.

1st Gen were individually hand stamped. Don't know about others.