In hopes of someone recognizing exactly what the first stone is, here are close-ups of the polished (actually, epoxy sealed) and the rough side.

amrap,
I suggest that Youtube is your friend in this situation, as there a a number of videos on using a tumbler that I think would be a great help.

It looks like the Sacramento Mineralogical Society's lapidary workshop has reopened, but I don't know if they're teaching the required Beginning Lapidary Class yet. I'd prefer to take the class and learn how to do this myself, but I don't want to wait until mid-2021 or whenever they're fully reopened.

Steve, let me contact the club and see what's going on as far as accepting new members and training them to use the club's equipment. If they're still going to be closed indefinitely, I'll accept your offer with gratitude if you let me pay you for your time and supplies.

If you really like the slab and want it for the back drops, I will offer if you send it to me in a small flat rate usps box, I can flat lap it for you and send it back when done.

That's a fun idea, but even using a nice printer (I use an Epson P600) the backdrop would obviously be a print.

I'm not trying to be obstinate or contrary at all here. I'll totally admit that I bought a slab without knowing what I'd need to do to make it look good in photographs, and that I may have bitten off more than I can chew. Were we not in Covid-land, I would have already joined my local lapidary club and taken their orientation/beginner classes.

If the answer is just that the slab needs to be "wet" to bring out its colors -- no worries, I'll happily try a clear coat or the epoxy recommended. If it needs a huge amount of labor and/or specialized equipment, that's cool too -- I'll shelve this slab until I have a chance to join the local lapidary club and get some basic hands-on education. If it's not feasible to get the slab looking as good as it did in the seller's photographs, then shame on me for not figuring that out in advance of buying it. Thankfully it was only a few bucks!

I am sincerely grateful for the patient help I've received on this forum in this and other threads. Thank you @irockhound and @R.U. Sirius! This is why I've contributed to the forum. I apologize if my questions have been frustrating.

🌟

What a stunner!

Really cool sphere. Tight, feathery lines and lovely pale blue ground.  Puts most Indian moss agate in the shade.

All terrific, particularly the Binghamite which reminds me of top quality petrified wood mixed with pietersite.

Superb stuff! I wish the Indian and Madagascan jasper-agates were this good in this size.