Determine Type of Fiber Already in Place

Hello,

I apologize for the silly question, but I can't find a solid answer to my question. I'm hoping someone here can help me out. I know very little about fiber

How do I determine the speed and type (OSx/OMx) of fiber that's already in place?

The cables in question do not conform to established color codes (dark green and dark blue) and OSx/OMx is not seemingly labeled anywhere on the jacket.

How do I determine what fiber I'm dealing with?

Appreciate your help!