I have a lot of new or pull off cogs from Shimano Dura Ace and/or Ultegra from cassettes.

Thing is that I cannot tell what type of cassette they belong to.
Does anyone know of a resource online that has a list of what the codes or stampings or markings mean?

Markings such as...
DE
DT
DD
DH
DX
DA
DF
DL
DG

And others like...
EA
EG
EH

7900? 7700? 7800?? How do I know?

The colors of the cogs vary too...brown to grey to polished.
Any significance?

Thanks in advance.