---
product_id: 222572366
title: "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"
brand: "blue marble"
price: "¥41428"
currency: JPY
in_stock: true
reviews_count: 9
category: "Blue Marble"
url: https://www.desertcart.jp/products/222572366-national-geographic-rock-tumbler-kit-3-lb-extra-large-capacity
store_origin: JP
region: Japan
---

# 3 lbs. extra-large capacity barrel 9-day programmable timer 3-speed motor for precise control 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

**Brand:** blue marble
**Price:** ¥41428
**Availability:** ✅ In Stock

## Summary

> 💎 Turn rough stones into polished gems — your personal treasure trove awaits!

## Quick Answers

- **What is this?** 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 by blue marble
- **How much does it cost?** ¥41428 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.jp](https://www.desertcart.jp/products/222572366-national-geographic-rock-tumbler-kit-3-lb-extra-large-capacity)

## 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

- • **All-Inclusive Gemstone Kit:** Includes 3 lbs. of raw rocks, 9 gemstone varieties, polishing grit, strainer, and reusable GemFoam for dazzling shine.
- • **Precision Tumbling Control:** Customize your polishing with 3-speed motor and 9-day timer for flawless results every time.
- • **Award-Winning Educational Fun:** From the Toy Association’s Toy of the Year winner, designed to spark creativity in both adults and kids.
- • **Effortless Shine with GemFoam:** Add GemFoam in the final stage to achieve museum-quality gemstone brilliance without extra hassle.
- • **Massive Capacity, Minimal Noise:** Extra-large 3 lb. barrel with leak-proof stainless steel lid runs 75% quieter than plastic alternatives.

## Overview

The National Geographic Rock Tumbler Kit features a durable 3-speed motor and a 9-day timer paired with a large 3 lb. capacity barrel, enabling users to transform raw rocks into polished gemstones. The kit includes 3 lbs. of assorted raw rocks, polishing grit, a strainer, and innovative reusable GemFoam for enhanced shine. Designed for both adults and kids, this award-winning kit combines educational value with creative fun, all while operating 75% quieter than typical plastic tumblers.

## Description

desertcart.com: 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 : Toys & Games

Review: FAILED AFTER 10 WEEKS - NOW A NICE PAPER WEIGHT - I purchased two of the National Geographic 3-pound tumblers thinking I would get well designed and built tumblers but I was wrong. Both tumblers have really crooked top pullies. As shown in the attached video, it looks like the pully could fly off the shaft. I think it is actually tight enough but is just really warped. I think the belts will wear out fast so I checked the manufacturer’s website (Blue Marble Store) for replacement belts but they don’t sell any. UPDATE: After 3 months the belts are badly worn. I was able to find replacements from a third party. I decided to take the risk and bought two more of these 3 Lb. tumblers. My last purchase was on Nov 24, 2025 and one of the motors completely failed on Feb 6 2026, only about 10 weeks of service. The return window closed on January 31, 2026. I always weigh the load to make sure the rock + water is not more than 3 Lbs. I don't understand how National Geographic can allow their name to be put on these poorly designed tumblers. I will be purchasing more of the KoolStone tumblers with their 2 year warranty.
Review: Good quality - Works great

## 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 |
| Best Sellers Rank | #39,017 in Toys & Games ( See Top 100 in Toys & Games ) #11 in Kids' Rock Tumblers |
| Customer Reviews | 4.5 4.5 out of 5 stars (4,940) |
| Is Discontinued By Manufacturer | No |
| Item Weight | 8.14 pounds |
| Item model number | NGTUMBLER3LB |
| Manufacturer | JMW Sales, Inc. |
| Manufacturer recommended age | 8 years and up |
| Product Dimensions | 12.76 x 10.31 x 6.69 inches |
| Release date | July 5, 2023 |

## Images

![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 - Image 1](https://m.media-amazon.com/images/I/91ThOdjpWqL.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

### ⭐⭐⭐⭐⭐ FAILED AFTER 10 WEEKS - NOW A NICE PAPER WEIGHT
*by J***P on October 12, 2025*

I purchased two of the National Geographic 3-pound tumblers thinking I would get well designed and built tumblers but I was wrong. Both tumblers have really crooked top pullies. As shown in the attached video, it looks like the pully could fly off the shaft. I think it is actually tight enough but is just really warped. I think the belts will wear out fast so I checked the manufacturer’s website (Blue Marble Store) for replacement belts but they don’t sell any. UPDATE: After 3 months the belts are badly worn. I was able to find replacements from a third party. I decided to take the risk and bought two more of these 3 Lb. tumblers. My last purchase was on Nov 24, 2025 and one of the motors completely failed on Feb 6 2026, only about 10 weeks of service. The return window closed on January 31, 2026. I always weigh the load to make sure the rock + water is not more than 3 Lbs. I don't understand how National Geographic can allow their name to be put on these poorly designed tumblers. I will be purchasing more of the KoolStone tumblers with their 2 year warranty.

### ⭐⭐⭐⭐⭐ Good quality
*by B***R on February 3, 2026*

Works great

### ⭐⭐⭐⭐⭐ 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!

## 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 Japan*
*Store origin: JP*
*Last updated: 2026-03-10*