It would be steel if it lights up…Do you have the shields removed?
yes 
Because if it’s not ceramic you would magnetize the bearing. Try sliding a magnet over a row of magnets to see why you wouldn’t want this in a yoyo bearing.
Make sure when you’re touching the bearing balls that you’re ONLY touching a ball. As soon as you touch the steel part of the bearing, it will light up.
Side note: don’t you guys have a multimeter you can use? 
I just look for the single dot on the bearing, that way I know it’s a Terrapin X ceramic, usually an S/C version.
That’s all I need to know!
True, but that dot fades away (I’m assuming you mean the red dot on the shield) and the center assist is too minuscule to even see. So I just keep mine in labeled bags. Haha
I track in my database what is where so I know. I can always re-dot the bearing. I always have Sharpies.
True. I never thought about redotting them. XD I have more bearings than yoyos so I have to keep them in bad anyways
If you look carefully you can see it, but yes it is shallow.
U-groove track bearings were designed to run on rails.
The only way I can see it is by seeing the machining marks around the yoyo. Haha
But does it work for you…
Yes, and I means around the bearing* the slight mark used to put the center assist in.
The outside is magnetic. Only the balls are ceramic
Touch a magnet to a bearing, especially ceramics, it will mess them up…