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A rock tumbler can expose the inner beauty of stones you find on your travels, at the beach or in your backyard, polishing their rough exterior to reveal layers and colors. This isn’t a difficult hobby, but it requires patience, a handful of supplies and accessories, and a bit of trial and error.
The two primary types of rock tumblers, rotary and vibratory, operate at different speeds and produce slightly different results. If you’re just starting out, consider a smaller, less expensive model to learn the tumbling process and find out what types of rocks give you the results you want. The more common rotary tumblers are best suited for polishing irregularly shaped rocks that have angles or points, though this process takes about a month. Vibratory tumblers shake rocks to polish them in as little as a week, but the rocks must be fairly round to begin with for best results.
The size of the tumbler determines how many rocks you can polish at once, and some high-end models have two tumblers for polishing twice as fast or tumbling rocks with different grit levels. If you have a small living space, you should also consider the noise level because some tumblers are quite loud.
We researched and tested rock tumbler kits and found the National Geographic Professional Rock Tumbler Kit to be the best for most people. Our experts recommend a single-drum model to begin with, though a double-drum tumbler is a worthwhile investment if you’re an avid rock collector.
Editors' Favorite
Skill: Beginner/advanced | Capacity: 2 lb | Settings: 3 | Timer: Yes | Includes grit: Yes
Making rock tumbling easy and educational, the National Geographic Professional Rock Tumbler Kit comes with everything you need to get started. Suitable for children aged 8 and up, it's able to polish 2 pounds of rocks at a time.
The rubber barrel is durable and has a tight-fitting seal that does a good job of preventing leaks. The barrel is also 75% quieter than plastic models. And the results are gorgeous. The unique GemFoam media creates a shiny finish and can be reused if you wash the grit off the cubes.
On the slowest setting, this tumbler can produce high-quality polished stones in a little over the usual four weeks. The two included belts are fairly durable, and customers say they can last over a year.
Most Comprehensive
Skill: Professional | Capacity: 2.5 lb | Settings: 3 | Timer: Yes | Includes grit: Yes
The Koolstone C1 Rock Tumbler Kit is a nice-sized tumbler that stands out for its all-rubber drum, which makes it one of the quieter models available — a major plus if you’re concerned about noise, especially if you have a small home. It includes basic accessories, a pound of rough stones and ceramic media, the last of which many other kits leave out.
The 2.5-pound barrel allows you to polish multiple rocks in a single batch. The tumbler also has a nine-day timer that automatically turns off the machine when it finishes. Its memory function saves your progress if the tumbling process is interrupted, though, so you don’t have to start over. Best of all, the clear, user-friendly display and control panel make operation straightforward even for beginners.
Leaks are unlikely with the lid’s rubber seal, so you don’t need to worry about setting the tumbler on various surfaces. If you follow the instructions carefully, it consistently produces shiny polished stones after a few weeks.
Great Value
Skill: Beginner | Capacity: 1 lb | Settings: One | Timer: Yes | Includes grit: Yes
Our 8-year-old tester loved using the National Geographic Hobby Rock Tumbler Kit with a bit of help from a parent. This beginner tumbler was easy to set up and produced great results after about a month (the longer the rocks tumble, the better the results — so patience is required ).
It includes a few basic tools like jewelry fasteners and strainer, and the guide takes you through the steps to get your rocks as shiny as you want them. The variety of included stones make for a good first batch, and the operation is simple enough to start tumbling on day one.
The seven-day timer is perfect for checking the stones at the end of each of the four stages. Its 1-pound capacity is large enough for casual rock collectors or jewelry makers. It has a few speed settings and is quieter than similar rotary tumblers.
We liked that the rubber drum not only muffles the noise but also makes the drum more durable than plastic models. However, our tester's mom says, "It's too noisy to keep indoors because it needs to be tumbling the rocks 24-7; you would definitely want to put it in a garage or somewhere outside." Despite that, this product was a hit. "It’s a great educational product for kids 8 and up to physically show them how a smooth gemstone is created," our tester's mom says. "You can also use it to make sea glass."
Best for Kids
Skill: Beginner | Capacity: 1 lb | Settings: None | Timer: No | Includes grit: Yes
Rock tumblers are a favorite for kids who collect rocks. This National Geographic Starter Rock Tumbler Kit is an ideal gift for a youngster interested in STEM but also works for anyone who wants a way to easily polish pebbles and semiprecious stones. It's got a simple, straightforward design with no controls, just a bright yellow drum lined in tire rubber to minimize noise. Plug it in to power it on and unplug the cord to stop.
The National Geographic Starter Rock Tumbler has a capacity of 1 pound and comes with a half pound of sample rough gemstones. It also includes a sieve and four bags of grit to get your gems smooth.
Jewelry settings are also included to help you make the most of your polished pieces. Like other National Geographic-branded merchandise, proceeds help benefit the National Geographic Society's mission of research and exploration.
Feature-Packed
Skill: Advanced | Capacity: 1 lb | Settings: 3 | Timer: Yes | Includes grit: Yes
Our top pick, the Dan&Darci Advanced Professional Rock Tumbler, works well not only as a first tumbler but also as one you can continue to use if you find that you really enjoy the hobby. The included guide makes it easy to get started, and the four grit packets are enough for your first batch.
The replacement belt drive ensures that you can use your tumbler for several batches, and you can purchase additional grit from the company’s website. You can adjust the speed to account for the type of rocks you’re using and how much polishing they need. It produces round, shiny stones after about a month of continuous use.
The price of this tumbler puts it in the middle of the range, and it’s an excellent value when you consider the included accessories: rocks, four levels of grit, strainer and jewelry fasteners.
After researching dozens of tumblers, we compared the functionality and results of the eight tumblers above and gave the National Geographic Hobby Rock Tumbler Kit a spin. We recommend this model for its easy setup and reliable results, even with your first batch.
Set up: The included instructions had us tumbling rocks quickly and only included a few steps: fill the tumbler with the provided rocks and grit, add water, then plug in the tumbler and set it to its maximum time of seven days. The longer you tumble the rocks, the better the results.
Noise: Rock tumblers are known for being loud. We found that it’s a good idea to put the tumbler in an accessible place where noise won’t be an issue, such as a garage.
Maintenance: We changed out the grit each week for a month, allowing the rocks to go through all four polishing stages. We checked it daily to ensure it was operating properly and that the belt had not slipped off.
Quality: At the end of the four weeks, the rough, jagged rocks were now much smaller polished rocks, resembling what you might find in a store. To make them extra shiny, we rubbed them with mineral oil.
Jewelry: We used some of the stones to assemble the included pieces of jewelry and a key ring, which were easy to make.
A. You’ll need grit to create friction, as well as tumbling media, usually smooth ceramic pellets, to ensure the rocks are polished evenly. You’ll also need a strainer to rinse the rocks, as well as water to add to the tumbler. A respirator and safety glasses are essential for protecting your lungs and eyes.
A. While this isn’t a problem that affects the polishing process, you should never pour the water from a tumbler or water used to clean rocks down the drain — doing so risks causing serious plumbing problems.
“Bruising” on rocks looks like chips, dents or cracks and is the result of the rocks banging into each other with significant force. If this occurs, try adding either more rocks or more media to fill up the tumbler and limit the movement of the rocks.
Rocks that don’t have a shiny polish or have rough or hazy areas can be the result of any or all of the following: not running the tumbler long enough, not adding enough media or not cleaning the drum thoroughly between batches.
A. You’ll have to brush up on your Earth science a little. Rocks should be from 5 to 7 on the Mohs scale of hardness, and all rocks in a batch should be of similar hardness. Popular types include rose quartz, tiger’s eye and jasper. You can also polish metal components and coins in a tumbler.
