---
product_id: 222572366
title: "National Geographic 3 Lb. Rock Tumbler Kit for Kids and Adult Beginners | 3 Lb. Capacity Barrel, 3-Speed Motor, 9-Day Timer, Rough Rocks and Polishing Grit, Rock Polisher, Geology Hobby"
brand: "blue marble"
price: "€ 318.62"
currency: EUR
in_stock: true
reviews_count: 13
category: "Blue Marble"
url: https://www.desertcart.hr/products/222572366-national-geographic-3-lb-rock-tumbler-kit-for-kids-adult
store_origin: HR
region: Croatia
---

# 9-day programmable timer for set & forget 3-speed motor for precision control Leak-proof stainless steel barrel with quiet operation National Geographic 3 Lb. Rock Tumbler Kit for Kids and Adult Beginners | 3 Lb. Capacity Barrel, 3-Speed Motor, 9-Day Timer, Rough Rocks and Polishing Grit, Rock Polisher, Geology Hobby

**Brand:** blue marble
**Price:** € 318.62
**Availability:** ✅ In Stock

## Summary

> 💎 Turn rough stones into polished treasures — your personal gem lab awaits!

## Quick Answers

- **What is this?** National Geographic 3 Lb. Rock Tumbler Kit for Kids and Adult Beginners | 3 Lb. Capacity Barrel, 3-Speed Motor, 9-Day Timer, Rough Rocks and Polishing Grit, Rock Polisher, Geology Hobby by blue marble
- **How much does it cost?** € 318.62 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.hr](https://www.desertcart.hr/products/222572366-national-geographic-3-lb-rock-tumbler-kit-for-kids-adult)

## Best For

- blue marble enthusiasts

## Why This Product

- Trusted blue marble brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Award-Winning STEM Fun:** Backed by the Toy Association’s Toy of the Year, this kit sparks creativity, critical thinking, and hands-on learning for all ages.
- • **Precision Tumbling Control:** Customize your polishing with 3-speed motor and 9-day timer—set it and forget it while your gems shine.
- • **Effortless Gemstone Creation:** Transform rough rocks into dazzling polished gems with ease, perfect for beginners and pros alike.
- • **Complete Starter Kit Included:** Get 3 lbs of assorted raw rocks, polishing grit, jewelry fastenings, and the exclusive reusable GemFoam for that ultimate sparkle.
- • **Durable & Whisper-Quiet Design:** Engineered with a leak-proof stainless steel barrel and noise-reducing tech, it’s 75% quieter than plastic models.

## Overview

The National Geographic 3 Lb. Rock Tumbler Kit is a professional-grade, beginner-friendly rock polishing system featuring a durable, leak-proof stainless steel barrel, a 3-speed motor with a 9-day timer, and a quiet operation design. It includes 3 lbs. of assorted raw rocks, polishing grit, jewelry fastenings, and the innovative reusable GemFoam polisher. This award-winning STEM toy fosters creativity and critical thinking, making it ideal for kids and adults eager to explore geology and craft their own gemstones.

## Description

desertcart.com: National Geographic 3 Lb. Rock Tumbler Kit for Kids and Adult Beginners | 3 Lb. Capacity Barrel, 3-Speed Motor, 9-Day Timer, Rough Rocks and Polishing Grit, Rock Polisher, Geology Hobby : Toys & Games

Review: It works great. - If you’ve never tumble rocks before (us), it’s fascinating to see the end products.
Review: Excellent Tumbler with Insufficient Supplies - I started using the National Geographic 3 lb. tumbler in March of 2021. I’m new to rock tumbling, so as I’ve been getting started, I’ve been studying best practices in hopes of maximizing my results. *** Edit *** I like this tumbler so much, I bought a second one. ***/Edit *** This tumbler is extremely well-made. The base, which includes the motor & control panel, is very sturdy. The barrel is exceptional, in that it is larger than other 3 lb. capacity tumbler barrels, and has a very effective sealing mechanism to prevent leaks. There is an extra drive belt included, for when the original belt wears out, or breaks. The overall operation of this unit is smooth, with minimal vibrations. Most of the sound comes from the motor, as the material of the barrel tends to absorb the sound of the rocks tumbling around inside. On speed 3 (the fastest speed), I measured 65 dB right next to the tumbler. Since a rock tumbler has to run 24 hrs. a day, seven days a week, it’s advisable to have it in a garage or basement, so you don’t have to hear it running. While it doesn’t vibrate excessively during use, there is enough vibration to cause it to creep around on a smooth surface. Best to set it on a rubber pad, or otherwise block the base, so it doesn’t creep right over the edge of your work bench. There are two features to this tumbler that make it unique. First, it has 3 speeds, and even the slowest speed is faster than most other tumblers. This must be taken into account when you are determining how best to fill the barrel & how long to run each tumbling cycle. The second unique feature is the shape of the barrel, which is less deep, but larger diameter than other tumbler barrels. The internal volume is actually larger than that of other 3 lb. tumblers. This allows you to put more rocks in each cycle, with more of the weight of the rocks concentrated in a smaller area & tends to increase the efficiency of the grinding action. Faster speeds & more efficient grinding cause the rocks to hit each other more often, which will shape and smooth them in a shorter period of time than with other tumblers. But it also may require you to cushion more fragile rocks (such as feldspar) with tumbling media (such as ceramic pellets) to prevent bruising. Consider the price of this item to be for just the tumbler, with the rocks & grit included for free. The rocks you get are literally a “mixed bag” of all different types & hardnesses. One of the cardinal rules of rock tumbling is to only tumble rocks of the same hardness & durability together in the same barrel. So you don’t want to mix agates with feldspar, for example. Once you separate the included rocks by type, you will find that there aren’t nearly enough rocks to fill the barrel with similar rocks. Best to order 3-5 lbs. of a single type of rocks (search for “tumbling rough” online) so you can fill the barrel correctly for the best results. After a bit of experimentation, I have found that this tumbler produces the best results when the barrel is 3/4 full. This is about 3 lbs., although the weight will depend on the density of the rocks in your barrel. The main consideration should be where the top of the rocks are, compared to the bottom of the lid. By measuring the depth of the barrel, you can easily make a gauge that will represent the correct amount of space to leave at the top. Too many rocks in the barrel will prevent them from tumbling freely, but too few will just bounce around in the barrel, instead of sliding & grinding against each other. If your barrel is too heavy, it will cause the motor to shut down & you will have to follow the steps in the instruction manual to get it working again. I have routinely filled the barrel with 3 lbs. of dry rocks (plus water & grit) without having it shut down. I have also found that I get the best results when I include some ceramic tumbling media to fill the gaps between the rocks (this helps to carry the grit for more efficient grinding & also to cushion the rocks.) The included grit & polish packets are insufficient to produce good results. Buy some bulk grit & polish from a rock shop (there are several online.) You will want 60/90 Silicon Carbide for stage 1 (about 4 tablespoons per load.) You will use much more of this than any other grit, as stage 1 can take several cycles to shape hard rocks, such as agate & jasper. Stage 2 requires 120/220 Silicon Carbide (about 4 tablespoons per load.) You will probably need to run one or two cycles in stage 2, until the rocks are smooth. Stage 3 requires 500 grit (either Silicon Carbide, or Aluminum Oxide) - about 4 tablespoons per load. This stage will probably only take 1 cycle & the rocks will start to show a slight gloss & feel really smooth. Stage 4 requires Aluminum Oxide polish (about 3 tablespoons.) This will generally be a single cycle (until the rocks are shiny when dry.) I have never used the included foam cubes. Instead, I run a burnishing cycle using 4 tablespoons of borax powder & a squirt of Dawn dish soap. (All stages require just enough water to almost cover the rocks.) I run stage 1 on speed 3 (fastest) in 4-day cycles. Empty the barrel, rinse the rocks into a bucket, & examine them. If all of the edges are rounded, set the rock aside for stage 2. If there are still rough edges or large pits, you will need to put the rock back into stage 1. Because most of the grinding happens in stage 1, you will have to add more rocks in each cycle to keep the barrel at 3/4 full. This requires a large enough supply of rocks to keep feeding the barrel. Six pounds of rough might yield three pounds of polished stones. When your pile for stage 2 is large enough, you can proceed. This may take a month or more. Once you move on to stage 2, things move faster. I run stages 2-4 at speed 1 (slowest) in 7 day cycles. Use the same process as described above to sort your rocks. When you finish stage 2, there should be no rough spots (usually 7-14 days.) When you finish stage 3, the rocks should feel very smooth & maybe slightly glossy (about 7 days.) If your rocks still aren’t shiny after 10 days in stage 4 (polish), you might consider trying another type of polish (such as Cerium Oxide, or Tin Oxide) for an additional 4 days. This is an excellent rock tumbler that comes with insufficient supplies. My advice is to buy the tumbler, throw out the grit & polish, order your rough rocks and grit/polish from a rock shop, and consider the included rocks as a bonus. There are many excellent resources available online, including YouTube videos & a forum called “Rock Tumbling Hobby.” If you are considering buying a rock tumbler, you should check these out. My most valuable resource has been a book called “Modern Rock Tumbling”, by Steve Hart. It covers everything involved in the tumbling process, with excellent advice for how to get good results. *** Edit *** The motor went out on my tumbler, but I e-mailed help@natgeotoys.com with a copy of my receipt, and explained the problem. They replied within the hour to tell me that they were sending me a new tumbler as a replacement (no charge.) The new tumbler arrived in two days. Superior customer service!

## Features

- CREATE YOUR OWN GEMSTONES - Rock tumbling is a hugely popular hobby for kids and adults! This professional rock tumbler makes it fun and easy to turn rough rocks into beautifully polished gemstones, thanks to its simple operation and durable design.
- A TUMBLER THAT'S MADE TO LAST - The durable motor has time and speed control settings so you can set it, and forget it. An improved, leak-proof barrel features a stainless-steel lid is 75% quieter overall than plastic tumbler barrels.
- INCLUDES 3 LBS. OF ROCKS & MORE - This tumbling kit comes with everything you need: 3 lbs. of raw rocks with 9 types of gemstones, 5 jewelry fastenings, grit, strainer & GemFoam for a dazzling shine!
- USE GEMFOAM FOR DAZZLING RESULTS - This rock tumbler kit stands apart from others thanks to our new, reusable GemFoam rock polisher! Add GemFoam and water to the barrel after your final tumbling stage and your gems will have incredible shine!
- AWARD-WINNING PRODUCTS - Blue Marble, winner of the Toy Association's prestigious Toy of the Year Award, proudly develops products that foster education, imagination, and creativity, with a U.S. support team to ensure a stellar experience!

## Technical Specifications

| Specification | Value |
|---------------|-------|
| ASIN | B08DL95CWL |
| Age Range Description | 8 years and up |
| Best Sellers Rank | #10,790 in Toys & Games ( See Top 100 in Toys & Games ) #7 in Kids' Rock Tumblers |
| Brand Name | Blue Marble |
| Customer Reviews | 4.6 out of 5 stars 5,058 Reviews |
| Educational Objective | STEM, Concept Development Skills, Hand-Eye Coordination, Critical Thinking, Reasoning Exploratory Skills |
| Included Components | Complete Rock Tumbler Kit, 3lb Assorted Rough Gems, 4 Stages of Polishing Grit,5 Jewelry Settings,GemFoam |
| Item Dimensions | 12.76 x 10.31 x 6.69 inches |
| Item Type Name | Rock Tumbler Kit - 3 Lb. Extra Large Capacity Barrel |
| Item Weight | 3.7 kg |
| Manufacturer | JMW Sales, Inc. |
| Manufacturer Maximum Age (MONTHS) | 1188 |
| Manufacturer Minimum Age (MONTHS) | 96 |
| Manufacturer Part Number | NGTUMBLER3LB |
| Material Type | Plastic, Stainless Steel |
| Model Number | NGTUMBLER3LB |
| Number of Items | 1 |
| Number of Packs | 1 |
| Set Name | Set |
| Size | One Size |
| Sub Brand | National Geographic |
| Theme | Geology |
| UPC | 816448028694 |
| Unit Count | 1 Count |

## Images

![National Geographic 3 Lb. Rock Tumbler Kit for Kids and Adult Beginners | 3 Lb. Capacity Barrel, 3-Speed Motor, 9-Day Timer, Rough Rocks and Polishing Grit, Rock Polisher, Geology Hobby - Image 1](https://m.media-amazon.com/images/I/91Ijz8tKNVL.jpg)

## Questions & Answers

**Q: Warranty on motor**
A: All our tumblers include a 1-2 year warranty.  For warranty assistance please contact us using the contact information found on the bottom of the package or in the instruction guide.

**Q: Why is it saying undeliverable to any of my US addresses?**
A: I experienced the same; it would not ship to my po box.  I had it shipped to my daughter's house; it seem to like her address.

**Q: What are the inside measurements of the 3lb barrel?**
A: Our 3 lb barrel is approximately 3.25" x 5.5"

**Q: How much does the barrel weigh?**
A: Our 3 pound barrel with lid weighs 2 pounds.

## Customer Reviews

### ⭐⭐⭐⭐⭐ It works great.
*by J***R on July 31, 2026*

If you’ve never tumble rocks before (us), it’s fascinating to see the end products.

### ⭐⭐⭐⭐⭐ Excellent Tumbler with Insufficient Supplies
*by M***N on June 15, 2021*

I started using the National Geographic 3 lb. tumbler in March of 2021. I’m new to rock tumbling, so as I’ve been getting started, I’ve been studying best practices in hopes of maximizing my results. *** Edit *** I like this tumbler so much, I bought a second one. ***/Edit *** This tumbler is extremely well-made. The base, which includes the motor & control panel, is very sturdy. The barrel is exceptional, in that it is larger than other 3 lb. capacity tumbler barrels, and has a very effective sealing mechanism to prevent leaks. There is an extra drive belt included, for when the original belt wears out, or breaks. The overall operation of this unit is smooth, with minimal vibrations. Most of the sound comes from the motor, as the material of the barrel tends to absorb the sound of the rocks tumbling around inside. On speed 3 (the fastest speed), I measured 65 dB right next to the tumbler. Since a rock tumbler has to run 24 hrs. a day, seven days a week, it’s advisable to have it in a garage or basement, so you don’t have to hear it running. While it doesn’t vibrate excessively during use, there is enough vibration to cause it to creep around on a smooth surface. Best to set it on a rubber pad, or otherwise block the base, so it doesn’t creep right over the edge of your work bench. There are two features to this tumbler that make it unique. First, it has 3 speeds, and even the slowest speed is faster than most other tumblers. This must be taken into account when you are determining how best to fill the barrel & how long to run each tumbling cycle. The second unique feature is the shape of the barrel, which is less deep, but larger diameter than other tumbler barrels. The internal volume is actually larger than that of other 3 lb. tumblers. This allows you to put more rocks in each cycle, with more of the weight of the rocks concentrated in a smaller area & tends to increase the efficiency of the grinding action. Faster speeds & more efficient grinding cause the rocks to hit each other more often, which will shape and smooth them in a shorter period of time than with other tumblers. But it also may require you to cushion more fragile rocks (such as feldspar) with tumbling media (such as ceramic pellets) to prevent bruising. Consider the price of this item to be for just the tumbler, with the rocks & grit included for free. The rocks you get are literally a “mixed bag” of all different types & hardnesses. One of the cardinal rules of rock tumbling is to only tumble rocks of the same hardness & durability together in the same barrel. So you don’t want to mix agates with feldspar, for example. Once you separate the included rocks by type, you will find that there aren’t nearly enough rocks to fill the barrel with similar rocks. Best to order 3-5 lbs. of a single type of rocks (search for “tumbling rough” online) so you can fill the barrel correctly for the best results. After a bit of experimentation, I have found that this tumbler produces the best results when the barrel is 3/4 full. This is about 3 lbs., although the weight will depend on the density of the rocks in your barrel. The main consideration should be where the top of the rocks are, compared to the bottom of the lid. By measuring the depth of the barrel, you can easily make a gauge that will represent the correct amount of space to leave at the top. Too many rocks in the barrel will prevent them from tumbling freely, but too few will just bounce around in the barrel, instead of sliding & grinding against each other. If your barrel is too heavy, it will cause the motor to shut down & you will have to follow the steps in the instruction manual to get it working again. I have routinely filled the barrel with 3 lbs. of dry rocks (plus water & grit) without having it shut down. I have also found that I get the best results when I include some ceramic tumbling media to fill the gaps between the rocks (this helps to carry the grit for more efficient grinding & also to cushion the rocks.) The included grit & polish packets are insufficient to produce good results. Buy some bulk grit & polish from a rock shop (there are several online.) You will want 60/90 Silicon Carbide for stage 1 (about 4 tablespoons per load.) You will use much more of this than any other grit, as stage 1 can take several cycles to shape hard rocks, such as agate & jasper. Stage 2 requires 120/220 Silicon Carbide (about 4 tablespoons per load.) You will probably need to run one or two cycles in stage 2, until the rocks are smooth. Stage 3 requires 500 grit (either Silicon Carbide, or Aluminum Oxide) - about 4 tablespoons per load. This stage will probably only take 1 cycle & the rocks will start to show a slight gloss & feel really smooth. Stage 4 requires Aluminum Oxide polish (about 3 tablespoons.) This will generally be a single cycle (until the rocks are shiny when dry.) I have never used the included foam cubes. Instead, I run a burnishing cycle using 4 tablespoons of borax powder & a squirt of Dawn dish soap. (All stages require just enough water to almost cover the rocks.) I run stage 1 on speed 3 (fastest) in 4-day cycles. Empty the barrel, rinse the rocks into a bucket, & examine them. If all of the edges are rounded, set the rock aside for stage 2. If there are still rough edges or large pits, you will need to put the rock back into stage 1. Because most of the grinding happens in stage 1, you will have to add more rocks in each cycle to keep the barrel at 3/4 full. This requires a large enough supply of rocks to keep feeding the barrel. Six pounds of rough might yield three pounds of polished stones. When your pile for stage 2 is large enough, you can proceed. This may take a month or more. Once you move on to stage 2, things move faster. I run stages 2-4 at speed 1 (slowest) in 7 day cycles. Use the same process as described above to sort your rocks. When you finish stage 2, there should be no rough spots (usually 7-14 days.) When you finish stage 3, the rocks should feel very smooth & maybe slightly glossy (about 7 days.) If your rocks still aren’t shiny after 10 days in stage 4 (polish), you might consider trying another type of polish (such as Cerium Oxide, or Tin Oxide) for an additional 4 days. This is an excellent rock tumbler that comes with insufficient supplies. My advice is to buy the tumbler, throw out the grit & polish, order your rough rocks and grit/polish from a rock shop, and consider the included rocks as a bonus. There are many excellent resources available online, including YouTube videos & a forum called “Rock Tumbling Hobby.” If you are considering buying a rock tumbler, you should check these out. My most valuable resource has been a book called “Modern Rock Tumbling”, by Steve Hart. It covers everything involved in the tumbling process, with excellent advice for how to get good results. *** Edit *** The motor went out on my tumbler, but I e-mailed help@natgeotoys.com with a copy of my receipt, and explained the problem. They replied within the hour to tell me that they were sending me a new tumbler as a replacement (no charge.) The new tumbler arrived in two days. Superior customer service!

### ⭐⭐⭐⭐⭐ Really Impressive Customer Service
*by A***R on October 21, 2024*

I purchased my first Nat Geo 3 Lb Professional tumbler in January. I liked it so much I now have several running and I run them every day. They're easy to fill, clean and are relatively quiet. I especially love the rubber barrel that cushions the rocks while they tumble and are much quieter than plastic or polyethylene counterparts. I've had very nice results polishing many different types of rocks and Mohs hardness levels. It's certainly easy enough to use that kids could enjoy this tumbler but it's also of high enough quality for adult enthusiasts. The first tumbler I purchased stopped running recently and after unplugging it and plugging it back in, it resumed running but much slower and would no longer run on 3 speeds. I sent an email to Nat Geo customer service (on a Sunday afternoon) asking if they could help and got an immediate response. The rep asked for proof of purchase and because it had been purchased within the last year, they sent me a new tumbler at no cost. It arrived THE SAME DAY! On a Sunday no less. That's what I call standing behind your product and excellent customer service. Very impressed!

## Frequently Bought Together

- National Geographic Rock Tumbler Kit - 3 Lb. Extra Large Capacity Barrel with 3-Speed Motor & 9-Day Timer, Kit Includes Rocks for Tumbling and Rock Polisher Grit, Rock Tumbler for Adults and Kids
- Blue Marble National Geographic Rock Tumbler Grit and Polish Refill Kit - Tumbling Grit Media, Polish Up to 20 lbs. of Rocks, Works with Any Rock Polisher, Rock Tumbler Supplies
- NATIONAL GEOGRAPHIC Rock Tumbler Refill Kit – 1Lb. Gemstones and Rocks for Tumbling including Unpolished Amethyst and Quartz – Rock Tumbler Supplies include Rock Tumbler Grit and Jewelry Accessories

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*Product available on Desertcart Croatia*
*Store origin: HR*
*Last updated: 2026-08-14*