Learn how to transform rough, natural rocks into polished gems. With some equipment and a little instruction, you’ll soon get the hang of this extremely satisfying hobby.
You’ve most likely seen tumbled rocks before: They’re often for sale in museum gift shops and they make frequent appearances in handcrafted jewelry.
Read on to learn how to start tumbling rocks in the comfort of your own home!
Why try out rock tumbling?
- Tumbled rocks are pretty. Plenty of people grow enamored with rock tumbling simply because it’s remarkably satisfying to transform rough rocks into shining gems.
- Like metal detecting, this hobby is one that gets you outdoors enjoying the fresh air. Hunting for good rocks to tumble is a great reason to take a hike or a long walk on the beach.
- Use your rocks to decorate. Tumbled rocks are incredibly versatile. You can use them as vase filler; incorporate them into jewelry; create keychains, magnets, paperweights, and other crafts; make holiday ornaments…the only limit is your creativity!
How do rock tumblers work?
Rock tumblers are very simple machines that have existed for several decades—though of course rock tumbling has always happened in nature!
Rocks out in the wild tumble through streams and encounter other rocks, gravel, and sand that, over a long period of time, smooth and buff them to perfection.
You can take control of this process, and speed it up considerably, with a mechanical rock tumbler.
Rock tumblers take raw, uncut rocks from their natural environment and transform them into polished gemstones.
Their popularity increased during the mid-to-late 20th century, in large part because of their use in making jewelry.
Over the decades, manufacturers have improved their designs, making tumblers that operate more quietly and have longer lifespans.
Rock tumbling machines have barrels that rotate continuously over the course of multiple days or weeks.
The barrel contains your rocks, along with water and grit, which slowly grinds down the rough edge of your rocks until they are smooth and shiny.
Ever used an exfoliating scrub in the shower and felt how smooth your skin was afterward? Grit does the same thing for your rocks.
Today, the most popular brands are Lortone and Thumler’s. Browse models from these brands to find the best rock tumbler that fits your needs.
Rotary tumblers vs. vibratory tumblers
In a perfect world, you could purchase both a rotary and a vibratory tumbler!
You’d start your rocks out in the rotary tumbler to shape them, then move them over to the vibratory to finish them off.
But if you’re just starting out with this hobby, you might not want to invest too much money before you find out how you like it. Or you might simply be on a tight budget.
If so, go for a rotary tumbler. These tumblers typically work best for beginners, and they actually do the work of reshaping your rocks into rounded shapes and doing the coarse initial grinding.
In contrast, a vibratory tumbler will only polish rocks rather than shape them.
That said, if your primary goal is only to polish your rocks without shaping them, a vibratory tumbler may serve you well.
One advantage is that vibratory tumblers are significantly faster, often finishing up the polish in just a week.
That said, I recommend a rotary tumbler for most beginners. These tumblers might work a bit slower, but they yield beautifully-shaped rocks.
Plus, if you’re hunting for your rocks out in nature, odds are you won’t be finding rocks that are already well-formed. A rotary tumbler is much better equipped to smooth down rough surfaces and grind off sharp edges.
For these reasons, the rest of this guide will focus on rotary rock tumblers.
And if you want to check out my guide to the best rock tumbler for beginners, follow the link.
A little more about selecting a rotary tumbler
These tumblers come in a variety of sizes and at a variety of price points.
What size should you pick? Depends on how many rocks you want to tumble at once!
You can also consider a double-barrel rotary tumbler. The advantage of a double-barrel machine is that you can simultaneously tumble two different kinds of rocks. But the disadvantage is then you have to clean two barrels instead of just one!
What about cost? How expensive is a decent rock tumbler?
As a general rule, you can expect to pay at least $75 for a quality rotary tumbler. Probably a little bit more.
In the $125-300 price range, you can find a number of excellent options on the market.
It’s not necessary to run out and buy a top-of-the-line professional tumbler that can handle five tons of rock. But if you’re interested in pursuing rock tumbling as a longer-term hobby, you should stay away from the super cheap options, which simply don’t provide the same results or last as long.
That said, low-capacity plastic tumblers have enjoyed some popularity. They’re cheap (around $50) and can give you or your kids a quick intro to the world of rock tumbling.
If you just want to try rock tumbling out once, an inexpensive plastic tumbler might be right for you.
Drawbacks? The plastic barrels are loud.
Think about it: You put a bunch of rocks in a plastic bucket and shake and roll it around. It’s bound to be pretty earsplitting!
And bear in mind that the tumbling process lasts for approximately four weeks. Unless you have the tumbler in its own soundproofed room or separate workshop, the noise might start getting to you.
Plastic tumblers also tend to have smaller barrels, meaning that you can only tumble small batches. Finally, plastic tumblers are less durable.
In contrast, higher-quality models have rubber barrels, which drastically reduce noise levels.
Paying a little more for a bigger barrel (or a double-barreled model) allows you to tumble larger batches of rough. Finally, if you want your tumbler to last for years, you need to invest a little more upfront.
Do I need any equipment besides a rock tumbler?
Yes! But don’t worry; you don’t need much to get started.
Grit: You will need four kinds of grit:
- 60/90 silicon carbide
- 120/220 silicon carbide
- Pre-polish aluminum oxide
- Polish aluminum oxide
These four different types of grit correspond to the four basic stages of rock tumbling:
(1) initial shaping of the rocks with coarse grit, (2) further smoothing of the rocks with medium-fine grit, (3) the pre-polish stage, and (4) the final polish.
I’ll discuss each of those steps in greater detail below!
You might be tempted to head to the beach and gather up some sand to use as grit instead—after all, it’s free! But sand generally is not hard enough to be an effective abrasive for most of the rocks you’ll be tumbling. It’s simply not an efficient form of grit to use (with possible exceptions if you’re tumbling softer materials).
You’ll also need some tumbling media, typically either ceramic or plastic pellets.
Let’s say you just have a small batch of rocks to tumble. Ceramic pellets act as filler to take up the extra space in your barrel, as well as providing some cushioning. You can reuse these pellets multiple times and wash them in between tumbling steps.
Plastic pellets also help to cushion your rocks as they tumble. These pellets facilitate the tumbling process and also help to protect your rocks by softening any impacts.
Plastic pellets can also be cleaned and reused, though some hobbyists find that they are harder to clean than ceramic.
One caution: only use plastic pellets in a rotary tumbler, not a vibratory one.
Finally, you need some other basic equipment such as buckets to contain your rocks.
You’ll also want a colander or screen of some sort, which will help you clean your rocks in between tumbling stages.
A field guide to the rocks and minerals in your region will also help you find good rocks to tumble; either buy one or check a copy out from your local library.
What kinds of rocks should I tumble? Are there any rocks I should avoid tumbling?
Simply put, you want rocks that are:
- Relatively smooth (not sandy or gritty feeling)
Now let’s get into each of those two basic qualities.
First, hardness. The Mohs hardness scale, developed by geologist Friedrich Mohs in 1812, ranks hardness on a scale of 1-10.
Softer rocks like talc get lower numbers (1), while harder materials like diamond are assigned higher numbers (10). Here’s a handy guide to the Mohs scale, courtesy of the National Park Service.
This scale gives a helpful list of rocks, alongside objects that are hard enough to scratch them.
So for example, talc is listed at 1, and gypsum at 2. Both are soft enough that they can be scratched by a fingernail (hardness of 2.5).
If you find a rock in the field and are wondering if you can tumble it, try giving it a scratch with your nails. If you can scratch it with just your fingernail, it’s too soft to tumble.
Quartz, on the other hand, comes in at a 7, so it’s much harder and cannot even be scratched by a steel nail—though it can be by a masonry drill bit.
Corundum and diamonds appear near the top of the Mohs scale; these super-hard materials are extremely resistant to scratching.
Now I’ve said that the rocks you want to tumble are hard—but just how hard? Corundum and diamond, for example, are simply too hard and definitely not recommended for beginning rock tumbling enthusiasts.
Rocks that are around a score of 7 on the Mohs scale are the best for our purposes.
Quartz is a popular pick. It’s the right hardness, and it comes in several different varieties (such as agate and jasper) that all shine up nicely in a rock tumbler.
For further information on the Mohs scale, and a useful list of common minerals and their hardness scores, check out this page on Geology.com.
Next up, smoothness. Choose rocks that have relatively smooth surfaces. Avoid tumbling gritty rocks.
Materials such as sandstone or any rocks that are very weathered are simply not good candidates for tumbling. For one thing, they won’t turn out well themselves, and for another, they’ll likely ruin the polish and shine of all the other rocks in your barrel.
Why? Because as they’re tumbled, they’ll shed little pieces of coarse grit. This becomes a problem when you’re trying to polish up your rocks with fine or ultra-fine powdery grit (see below for the stages of rock tumbling).
Allowing coarse grit into your tumbler barrel at this stage will scratch up the other rocks.
As you gain experience with rock tumbling, you’ll learn how to tell quickly if a particular rock isn’t suited for the tumbler. But for now, remember that if a rock feels gritty, it’s probably best to toss it out.
You can also test rocks by rubbing them together. If one produces little particles, it shouldn’t be tumbled.
You should also avoid tumbling rocks that have small cavities, pits, or voids.
Pieces of grit will likely enter and stick in them, which isn’t particularly attractive. If the stuck grit reemerges during the polishing step, it can damage the other rocks in the barrel.
In a similar vein (no pun intended), stay away from highly fractured rocks, which are liable to crumble in the tumbler and scratch up other rocks.
Overall, look for rocks that are already relatively smooth with no extremely jagged edges.
You’ll achieve your best results if the raw, rough material you place in your tumbler is high quality.
What are some of the most popular kinds of rock to tumble?
Many people like:
- Quartz, which has several varieties (amethyst, agate, smoky quartz, tiger’s eye, jasper, citrine, aventurine, carnelian, and others)
- Petrified wood
How do I find rocks to tumble?
You have two basic options: finding raw material out in nature, or purchasing rough, either online or in a specialty store.
Many rock tumbling hobbyists enjoy hunting for rocks in the wild—it’s a great excuse to get outside and learn more about the natural world.
Plus, you may feel as if you have a more personal relationship with rocks that you found yourself.
Similar to hobbies like metal detecting, searching for natural rocks combines the thrill of the hunt with the great outdoors. You’ll need to do your research first.
First, learn what kinds of rocks are common in your area. For example, agate is quite common in the western United States.
If you live in Oregon, Montana, Wyoming, or Arizona, you’re in luck! A field guide to rocks and minerals can start you off on the right track and avoid a lot of frustration.
A good field guide will also teach you how to identify different rocks. With some practice, you’ll soon develop a good eye for distinguishing promising specimens from the rest of the rough material out there.
Where to search? Rocky beaches, lakeshores, and other coastal areas are usually excellent rock-hunting locations. But again, for more specific recommendations, you’ll need to check out a guidebook for your region.
Some people purchase rough instead of sourcing it directly from nature.
Maybe you live in an area without a great selection of rocks. Or maybe you’re itching to try tumbling a specific material: Do you love the rich blues of lapis lazuli or the deep greens of malachite? Probably best to purchase some rough and go from there.
Step-by-Step: How rock tumbling works
Now that you’ve acquired your rocks, tumbler, and other materials, it’s time to get started! Here’s what to do:
1. Shape your rocks
This process uses coarse grit and typically takes around a week. What’s involved?
- Fill your barrel with rocks so it’s around 2/3 full. If you don’t have enough rocks for this step, or if your rocks are fragile, add ceramic or plastic pellets as filler and cushion.
- Add coarse grit, approximately two tablespoons per pound of rock.
- Add enough water that your rocks are almost fully submerged.
- Close your barrel. Bear in mind that rock tumblers have maximum weight capacities, so if you’re concerned that your barrel might be too heavy, weigh it first.
- Attach the barrel to your tumbler and get started tumbling.
- In a few days, check in: Are your rocks shaping up well? If not, give them some more time in the tumbler.
- The coarse grinding and shaping process should take about a week. Once you’re happy with the shape of your rocks, remove them from the barrel and clean them off—don’t leave any grit clinging to them, as this will contaminate the next stage.
- Clean your barrel thoroughly with soap and water to remove all traces of the coarse grit. The next stage involved finer grit, and you don’t want any coarse grit left.
- Dispose of any slurry, grit, or mud somewhere other than down a sink drain. Slurry will seriously mess up your pipes.
2. Tumble again with finer grit
This process, which also takes about a week in a rotary tumbler, will remove scratches and pits from your rocks.
- Place your rocks back in the barrel, along with pellets (either new pellets or very thoroughly cleaned pellets from the previous step) if necessary.
- Add in your finer grit and water.
- Start up your tumbler!
- Check in once a day to see how things are progressing. Expect the process to take up to about a week.
- Once you’re happy with your rocks, remove them from the barrel and rinse them off.
- Clean your barrel again.
3. Now comes the pre-polish stage
You’ll be using aluminum oxide grit to make your rocks smooth and shiny.
- Place rocks back in the barrel, along with pellets, grit, and water.
- Check in regularly; expect the pre-polish stage to take up to a week.
- Once your rocks are showing a good bit of shine, remove them from the barrel, rinse them off, and clean your barrel again.
4. Polish your rocks
Now you’ll use ultra-fine, powdery grit that will really make your rocks shine.
- Back in the barrel! This time using your finest aluminum oxide grit.
- Pellets are a good idea to use here (if you haven’t already been using them) to add an extra layer of protective cushioning for your rocks.
- Once again, in a rotary tumbler, this stage takes about a week (less time if you use a vibratory tumbler).
- Decide if you want to…
5. Burnish (optional).
This stage adds extra sparkle.
- There’s no grit involved this time. Instead, most people use a material like borax (found in the laundry section of your grocery store) or soap shavings. Make sure you pick a simple soap that doesn’t have a bunch of chemical additives that will damage your rocks. Add approximately 2 tablespoons of soap or detergent per pound of rock.
- Put everything in your barrel, connect it to the tumbler, and get it started!
- You’ll see the effects after only one day, but you can leave your rocks in a little longer for even better results.
Finally, marvel at your silky smooth lustrous rocks!
Some extra rock tumbling tips:
Cleanliness is essential!
Make sure to clean everything—the rocks, the media, the tumbler barrel, and its lid—in between each step in the tumbling process.
If you forget to do this, you’ll end up with a nasty slurry of finely ground rock swirling around, making it impossible to get any sort of decent polish on your rocks.
You might also end up with coarse grit contaminating the barrel during the later stages, which will ruin your rocks’ polish.
So make sure your equipment stays clean. You simply can’t be too careful of methodical here.
Keep track of your rocks
As you read in the steps above, tumbling follows a fairly regular schedule.
Each of the 4 basic steps takes about a week in a rotary tumbler, and you don’t to lose track of time.
Whether you set reminders in your phone, write in your calendar, or keep a dedicated rock tumbling notepad is up to you.
Cushion your rocks properly while tumbling
If you put only a bunch of large rocks in the tumbler, they will smack against each other, leaving microfractures all along the outsides.
These fractures are especially apparent with rocks like quartz and obsidian, as they will show white areas of damage where they are hitting other rocks.
To make sure this doesn’t happen to you, use small ceramic media or plastic pellets as a cushion. This will reduce damage and enhance overall polish.
More on loading your tumbler barrel
If all of your rocks are large, then you will definitely need to add smaller items, either rocks or ceramic tumbling media to fill in the gaps.
Your barrel should end up at least 2/3 full of rocks (and no more than about ¾ full).
If it is too empty, the rocks will be thrown around too much and bruised.
Again, if you don’t have enough rocks to fill the majority of your barrel, you should add ceramic media as filler.
Finally, more is not always better
It can be easy to say to yourself that more tumbling is going to lead to better polishing. This is not true.
Even as you polish your rocks, there are a few tiny granules making their way around your tumbler, and if you leave your rocks in there for a whole month, they will come out scratched, maybe even worse than they started.
Typically, a solid week in polishing will be just the right amount to get maximum polish without any abrasive damage from over-polishing.
How to avoid common problems:
All of this sounds great, and it is, but many people run into issues when they first start tumbling rocks.
Let’s go over a few common missteps that beginners make and how to deal with (and ideally avoid) them.
Should I include this gritty rock?
Gritty rocks are your enemy. If you have a single rock in a tumbler which is shedding grit, none of the rocks will take a polish.
Check your rocks individually, and even rub them together. If a rock loses a fine, dusty layer every time you rub it, discard that rock.
Send it into orbit with the next SpaceX launch, throw it into a volcano, or shoot it from a cannon: Whatever you do, don’t put it in your tumbler.
As a rule, rocks which are very weathered will create a large amount of grit, so avoid those. Just make sure to check your rocks in advance.
There’s not much worse than spending all that time tumbling only to find out that you had one gritty rock ruin the whole batch.
Some of my rocks look a bit funny; they seem to contain multiple materials, with little pieces stuck into the larger rock. What to do?
You’re likely noticing that some of your rocks have inclusions, which often cause issues in tumblers. Inclusions are pieces of a different type of rock embedded into the larger rock.
These two different types of rock will almost never have identical hardness, so you will end up with an ugly final polish, with some parts shiny and others eaten away by the polishing medium.
Rocks with inclusions will often end up looking like a decayed tooth, so avoid tumbling these.
What about rocks with little pits in them?
Rocks with voids or small cavities also don’t perform well in a rock tumbler. Again, it’s best to identify these troublemakers early and toss them before you get your tumbler going.
It’s always unfortunate when you find an otherwise pretty rock and have to give it a pass—but there’s plenty of other rocks out there!
What’s the problem with rocks that have pits? They tend to attract pieces of coarse grit, which make their way inside cavities while the rock tumbles.
These pieces of grit sometimes remain stuck, leaving the finished rock with an unsightly flaw. And sometimes the grit comes unstuck during the later stages of tumbling.
When this happens, the piece of rogue coarse grit can scratch and damage the other rocks.
I’m guessing rocks with a ton of fractures are also out?
Yep! You should also avoid tumbling rocks that are very weather-beaten or fractured. They’re at risk of breaking up further in the tumbler and scratching other rocks.
Do I really have to clean out the tumbler in between every stage?
Yes: not only the tumbler, but all of your materials including the rocks themselves and the media should be thoroughly cleaned.
It’s also very important to avoid cross-contamination among different kinds of grit.
As you learn more about this hobby, you’ll likely develop a system that works for you to keep everything clean and in its proper place.
I’m in a hurry and want to tumble all of my rocks together to speed things up. They’re different types and levels of hardness—but will that really affect the final polish?
Mixing together a bunch of different rock types in a tumbler barrel is not a good idea.
You’ll get the best results if you stick to this basic rule of thumb: sort your rocks and only tumble one type at a time.
If you want to expedite the rock tumbling process, consider purchasing a double-barreled tumbler so you can polish two batches simultaneously. Otherwise, remember that rock tumbling is a hobby best enjoyed with a bit of patience.
Can I tumble other materials like glass or coins?
Yes! When you decide to get into this hobby, you’ll soon realize that you can tumble a lot more than just rocks.
Two of the most typical things to tumble are glass and coins. Naturally the procedure for tumbling these items is somewhat different from the process of simply tumbling rocks.
First, let’s look at how to tumble glass
If you really like the look of sea glass which you find at the beach, then tumbling glass is definitely for you.
The ocean naturally tumbles glass over the years, giving the old shards a wonderful, rustic appearance. Beach glass is perfect for decorations around the house, or even jewelry.
So how can you make this at home on your own time? Most importantly, be careful.
Glass is really sharp and a sliced up hand will pretty well ruin your day. Please wear gloves while handling glass, especially since glass for tumbling is in shards with all sorts of jagged edges to give you new scars.
Another important quality in tumbling glass is thickness.
In general, glass which is less than a quarter inch thick will simply fall to dust in a tumbler, so unless you want glass sand, stick with thicker pieces.
Glass is somewhat stronger than seashells, but not nearly as strong as a rock like quartz, so you need to be careful while tumbling, especially in the first two steps.
Honestly, you can often get away without even doing the initial step of shaping with a very coarse grit. If you do choose to use a course grit, go easy on it.
Make sure to check your glass pretty often in this stage, and if you are using glass closer to that quarter inch cutoff, be careful not to break it apart.
After that, you can pretty much proceed as normal with your tumbling; just make sure that at each individual stage, you use plenty of filler, or the glass shards will chip each other.
Overall, tumbling glass is pretty straightforward. Once you’re done, you should have a beautiful handful of sea glass, perfect for decoration, pot filler, or, if you really want to tumble a lot of glass, a beautiful mulch or path material for your yard.
Now what about coins?
First of all, a warning. If you find or inherit old coins, or for that matter any coins which may have value beyond their monetary value as currency, do NOT tumble them.
Do NOT clean them. Do NOT change anything about a collectible object, ever, or it will likely lose its value.
If you find an 18th-century French coin outside Pittsburgh, and you, ah, spruce it up a bit, you have just destroyed any collector value it once had.
Coins, or for that matter just about anything with a collector following, are worth the most in the condition they are found.
That said, say you just want to tumble some modern coins to make sure a coin machine or a bank will accept them. Or you’re 100% sure you want to keep these coins for your own personal enjoyment and decide you want them super shiny. Fair enough.
First, you’ll need to separate your coins by their types.
Copper and zinc should never mix in a tumbler, as they will damage each other.
Pennies made before 1982 are copper, so separate them out and tumble them on their own.
Next, any dimes or quarters made before 1965 are made of silver, so tumble these separately as well.
Once you’ve sorted your coins by their metals, you can begin tumbling.
A lot of people don’t actually use normal tumbling medium for coins, instead preferring aquarium gravel or even dish soap.
Also, with coins, you should only have to tumble them for a few hours at most.
And now you have handfuls of nice, shiny coins ready to take to the bank where you can turn them into, well, useful money. Jokes aside, tumbling your coins is a solid way to make sure that stupid vending machine at work takes them this time, or to make bank workers’ jobs a little bit easier.
Just remember, please, please, don’t put collectibles in your rock tumbler.
Where to go from here:
It’s time to find some more rocks and get a new batch started! But in the meantime, here’s a few ideas for what to do with your newly polished rocks:
- This Popsugar tutorial shows you how to create cabinet hardware with gemstones. Transform your tumbled stones or glass into gorgeous drawer pulls, and bring a plain old cabinet to life as a true statement piece.
- Follow the simple instructions on Design Love Fest to create a striking mirror surrounded by your gems. Or take inspiration from The Crafted Life and add personality and sparkle to your picture frames.
- Learn from Fall for DIY how to convert your polished rocks into unique handcrafted necklaces.
- Or follow this Squirelly Minds guide to turn your gemstones into simple but eye-catching rings.
Many people who give rock tumbling a try soon find themselves learning additional hobbies or crafts!
Whether you’re interested in crafting jewelry, using them as magnets or paperweights, decorating items for your home and garden, or making personalized gifts for your friends and family, you’ll find that your burnished rocks are up to the task.
Or if you prefer, you don’t have to do anything with them at all once they’re out of the tumbler.
Beautifully polished stones make great decorative pieces even just placed on the mantel or collected in a glass bowl.
Feeling generous? Give away a rock or two to your family and friends.
Feeling superstitious? Pick out your favorite stone and carry it with you for good luck!
The only limit here is your imagination. And a fresh batch of polished rocks will surely spark your creativity.
Whether you’re a natural magpie with an eye for shiny things, a huge fan of natural history, or simply someone who enjoys learning new skills, you’ll find that rock tumbling is a wonderful and fulfilling hobby.
As you learn more, you’ll develop your craft, learning how to identify different kinds of rocks and polish them up to their highest potential.
Along the way, you’ll gain a whole new appreciation for the beauty of the natural world.