Not sure there are multiple answers as the point of "stage 2" is to move stage 1 rocks further towards polish.
Stage one is where everything noteworthy happens until you get to the polish stage. All steps in between are to lessen/reduce the scratches left on your rocks from the coarse (previous) grit.
I did a run of obsidian a while back starting with two 15 pound barrels full of rocks. Pulled rocks from the barrels after each grit step to have "perfect" examples of what each step should accomplish. Ended up with a 12 lb barrel full that went to polish.
If I ever refine my photography skills I would like to post a thread on what rocks should look like after each grit.
The progression is not remarkable - other than the surface scratches on the rocks become finer and finer with each step. Not remarkable, but very noticeable - especially under magnification.
Rocks should pretty much be flawless after stage 1 (depending on your expectations or lack of) with the final shape you are after and only surface scratches which finer grits can lessen.
With experience tumbling rocks, you will know what the scratches from each grit will look like. Given a tumbled rock one should be able to tell the last grit it went through.
60/90 grit scratches are pretty easy to tell from 120/220 scratches and definitely from 500 grit scratches.
The only difficulty identifying the last grit the rock went through would be if the rock(s) tumbled longer as the grit broke down. Meaning, 120/220 grit scratches will look like 500 grit scratches (given time) as the 120/220 grit breaks down.
I guess what you are looking for is that the scratches left from your coarse (or previous) grit have been reduced by the next
Thank you for the reply. I just wasn't sure what to look for but I do now.
thanks again.