Has anyone worked with NC rough gems?

Another from the land with no rocks! (Meaning Florida - panhandle, myself).

Like others also recommended, I'd get a rotary to run any coarse in. Most vibes won't do 60/90 coarse without risking catastrophic damage to the barrel.

I have no idea where the ruby/sapphire that I've been messing around with came from originally, but it's the same sort of variety that you're talking about. Some of my before/during pics are in this thread.

Since my last post in that thread, I've taken most of what I had still in any stage of regular stuff and put it into the diamond, and then took that backwards from 14k mesh to 4k to see if they'll even out a little more before moving forward again.

My own advice based on what I saw with mine would be to not waste a lot of time tumbling yours with Silicon Carbide grits, especially if what you're wanting is to see is whether any ultimately have cab potential. You can see what mine looked like after a month of coarse 60/90 (in a rotary) - and you probably wouldn't even need that long to wear off any matrix and get an idea of the character of the stones when they're wet. You can also see from mine that while the SC grits will wear the stones down, they don't seem to be nearly as good at smoothing them out.

My guess on that is that the SC grit is probably just hard enough to scratch at the stone and wear it away - but not hard enough to wear it down quickly enough so that the surface smooths out. What you can see from mine is that the layers that make up the stone are eroded away, but not smoothed - and they just kept doing that, wearing away but not smoothing over no matter how long they were left in. A few of them I did take all the way to regular polish and those are getting a somewhat smooth surface now, but the ones in diamond have far surpassed them, even those that were in much worse shape when they went in.

[And, just for grins I threw a completely rough piece in with the 4k mesh diamond group a few days ago, just to see what happens with it vs. what happened with the ones that were started in SC grits. This particular one had no matrix and looks as though was cut from a larger piece - it's a hexagonal slice with part broken off (but the slice isn't even, it almost looks like they took three passes at it with a saw because there are three slightly differently-angled levels to the cut face). I don't expect anything from it, starting it in such a fine-mesh level, I'm just curious to see what it does. I'll also take more pics when I run out of 4k and have run that group through a burnish before taking them all back to 14k mesh.]