Tumbling Opal

I've tumbled them, and there is nothing unusual. I've put them in with other crystalline quartzes, such as amethyst, rose quartz, etc. I think I added some ceramics in the later stages to cushion, though.

Susan

Ed, if this helps, these are the opals that just came out of my tumbler today.
Australian Opals on left, the different colored ones on right are Ethiopian hydrophane and Turkey opals that did not finish polishing the last tumble run (the Aussie opals came from Christopher1234)- note: all below opals are damp, picture shot in filtered sunlight:


The lumpy pitted ones were not put in until the final polish stage. I did not want them fully polished, I wanted them a bit shiny so I could see where the fire was, since I plan to save them for carving.

Here's what fully polished opals in a tumbler look like (some were preshaped, others were not, some started out cracked, but all of them shine:)). Note, all below opals are dry, picture shot under LED lighting (the fires do not show up under normal lighting on these):

I've tumbled it in the past. I ran it with agate and quartz in my lot o and it turned out great. It can have flashes of green in it, but it's like the irredescence in the hairline cracks in quartz, not true fire.

Sorry, girasols. The shop I bought them at in kent, wa had them labeled girasol quartz. Probably to prevent confusion.

There are both girasol opals and girasol quartz. The stuff the Rockshed sells as "girasol opal" is really girasol quartz. (said to save the original poster from complete confusion)

After thinking about it a bit, I think the best idea is if you tumble ANYTHING called 'opals', you should err on the side of caution and tumble them as a dedicated batch alone (with ceramic or glass filler material).

I posted my experience because there's no reason for anyone else to suffer the loss I did, but I learned a lot from it and I knew the risk. If it helps prevent others from making the same mistakes, it may make me feel better:).

I also need to point out that one reason I didn't lose more of the opals was the outstanding advice from the various threads on this tumbling forum from the knowledgeable people here.

As you can see, I had almost no loss from the 2nd batch, because I learned so much from the first batch. But in every case, it was what I learned here that saved me a lot more expensive trial and error.

Just because you 'can' do something (maybe), doesn't mean you should. Anything called 'opal' means it's going to be a bit pricier or perhaps a bit nicer than others of its type. It should probably be dealt with separately.

There can be misinformation on the web (like the site Geoff found, calling yellow, orange and red fire opals 'girasol'!), just better to err on the side of careful, especially if you are worried about the stones.

So, if it says 'opal', tumble it by itself, you can't lose anything that way:).

Hi Charlie:).
First, I'd pull out the 'best' pieces that you may want to cab later, or pieces with obvious cracks. Those cracked ones ARE going to split, and if the opals have any value, it might be better to opticon them and then cut, rather than let them just break apart into sand.

My main goal in tumbling them was to get a shine on, to see if some stones with no apparent fire could be coaxed into showing some, and to get rid of excess dirt and matrix. Tumbling won't help much with pitting, other than to make it worse.

I started the opals in 500 grit, in a Vibe tumbler, I don't have a rotary, and I don't think I'd try opals in a rotary anyway, based on what others have said.

I was worried that the 220 grit would take too much off the opals... some of the ones I tumbled were SMALL (under 2 carats in some cases).

Starting with 500 grit, I still watched them... my goal wasn't to shape the opals, it was to get a polish, even if they were rough with pitting. If they have fire, someday you may want to cab them, and removing a lot of stone means less to work with later. On the not cabbables, I thought I might want to carve them later... so again, the shape was no big deal.

That said, those that you will make doublets or triplets from, I wouldn't tumble, because you can't predict WHERE the material is going to rub off of, and sometimes, it's the best parts. That said, I did not notice potch coming off any differently than the firey parts. I would say that it removes at the same rate. It's just more noticeable and painful when it's the fire part vanishing.

Oh, I would NOT put ANY boulder opal in a tumbler unless you are prepared for all that matrix to disappear. The matrix is often very soft, you'd end up with holey completely unuseable boulder opals.
For boulder opals, I'd slice them, then polish as is, the tumbler would undercut them into a big mess.

As soon as I saw that the dirt and matrix was mostly gone, I immediately washed the whole batch and put into 1000. That made me feel a little safer about the abrasion.

I used about 1/2 a tsp of borax AND a 1/2 tsp of Cascade dishwashing detergent in all my batches. I find that that makes rinsing very easy, and if it doesn't affect opal fire, I can't see why it would affect anything else. I haven't seen anyone else recommend doing that, so do it with a grain of salt, or use ivory soap flakes (I didn't have any).

At the 1000, I don't bother rinsing again, I added 1/2 a tsp of tripoli the next day, and then let it run til the rocks looked almost polished (about 2 more days). Then I added a spoonful of polish. If you still had any mud or matrix when you started the 1000, you may want to wash the batch at least once more before going for the polish.

That's it. The only real caveat would be that you use NO other stones in there with the opals. The only filler (and best filler), should be ceramic media OR glass. My first batch, I didn't have any ceramic media yet, and I threw in all excess glass. As the levels fell lower, I started to panic, and threw in MORE glass, but all I had left to toss in there were beads. Well, my opals got STUCK inside the bead holes, and smashing the beads later to get the opals out resulted in some smashed precious opals. So don't use any glass beads as filler. Actually, don't start the batch unless you have enough ceramic filler to almost fill the barrels FIRST, so you don't run low. And, if you buy new ceramic media, I'd break them in for a few days in a regular batch of rocks, so there's no sharp edges for your opals.

Only last caveat about opals. They are so temperature sensitive it's unreal. Be very very careful rinsing, and try not to TOUCH any with your hands until they have sat a few hours at room temperature. I pulled 2 out for some hand shaping... and out of all the opals, guess which ones cracked? Yep. Those 2. Of course, I went from 40 degrees to holding them in 97 degree hands, to hitting them with heat friction from the dremel too. But they were wet, and I only hit them for a few seconds with the dremel. I know well enough to keep the dremel moving and not sit in a spot building heat. Even so, those 2 cracked. I am convinced it was the heat from my hands, there was no other common denominator. Some people would say that's not possible, well, it happened, and I'm not going to keep breaking opals to prove the point:).

So when rinsing, pour into a collander, and rinse with a hose or something. Then pour carefully into a container (onto paper towel or towel), drain the water out, and take it inside to room temperature to dry. If you have to hasten drying, dry with a towel, don't TOUCH them with your hands until they have sat in room temperature a while. I try not to touch them at all until after they've dried in the jar inside the house.

Opals are probably the most temperature sensitive stones on earth, but if you are careful about that, they tumble just fine:). Hope that helps!

Hi...I have bought about $5000 worth of opals African /Australian opals straight from the mines so th here's lots of clay/Dirt sometime
On the stones.
I've tumbled and used a drumel ..with the drumel it took forever with many different grits of sandpaper+diamond cutter then a diamond polish. ..my results better but took three days to work on one piece....Can't afford a lapidary machine. .what do u use for tumbling ...I've ordered normal 5-6 step grits when tumbling. ...it seemed like I lost a ton of bulk..plus my results was nothing like I see in your picture when I tumble ... please give me pointers on how to tumble or what you use to tumble
I've bought various special polishs
But haven't tryed yet cause I'm afraid all my beautiful opals will get wasted like my last tumble! I had some beautiful purple and pearly blue Australian opaline bone that got ruined in my last tumble too! Please help I want to make jewelry but it looks like it's back to the drumel...please hlp !

Has anyone tried to tumble Bolder Opals? These have a lot of color.