---
product_id: 222772348
title: "National Geographic Hobby Rock Tumbler Kit – Durable Leak-Proof Rock Polisher with 7-Day Timer, Complete Rock Tumbling Kit with Grit, Jewelry Settings & GemFoam Polish, Educational STEM Science Kit"
brand: "blue marble"
price: "€ 102.15"
currency: EUR
in_stock: true
reviews_count: 8
category: "Blue Marble"
url: https://www.desertcart.ie/products/222772348-national-geographic-hobby-rock-tumbler-kit-durable-leak-proof-rock
store_origin: IE
region: Ireland
---

# 7-day programmable timer GemFoam polish for mirror shine leak-proof stainless steel barrel National Geographic Hobby Rock Tumbler Kit – Durable Leak-Proof Rock Polisher with 7-Day Timer, Complete Rock Tumbling Kit with Grit, Jewelry Settings & GemFoam Polish, Educational STEM Science Kit

**Brand:** blue marble
**Price:** € 102.15
**Availability:** ✅ In Stock

## Summary

> 💎 Turn rough rocks into polished gems — your personal treasure factory awaits!

## Quick Answers

- **What is this?** National Geographic Hobby Rock Tumbler Kit – Durable Leak-Proof Rock Polisher with 7-Day Timer, Complete Rock Tumbling Kit with Grit, Jewelry Settings & GemFoam Polish, Educational STEM Science Kit by blue marble
- **How much does it cost?** € 102.15 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.ie](https://www.desertcart.ie/products/222772348-national-geographic-hobby-rock-tumbler-kit-durable-leak-proof-rock)

## 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-in-One Gem Lab:** Includes 1/2 lb rough stones, 4 grit types, GemFoam, and jewelry settings
- • **Award-Winning Quality:** Toy of the Year winner with US-based support for flawless experience
- • **Leak-Proof Durability:** Stainless steel lid and barrel keep messes out and polish in
- • **STEM Meets Creativity:** Hands-on science project that turns erosion into dazzling gems
- • **Set & Forget Precision:** 7-day timer lets you run long cycles without babysitting

## Overview

The National Geographic Hobby Rock Tumbler Kit is a durable, leak-proof rock polisher featuring a 7-day programmable timer and a stainless steel barrel with a secure lid. This all-in-one STEM kit includes 1/2 pound of rough stones, multiple grit types, innovative GemFoam polish for a brilliant shine, and jewelry fastenings. Designed for ages 8+, it offers an engaging, educational experience that mimics natural erosion, perfect for hobbyists and families seeking a creative science project. Winner of the Toy Association's Toy of the Year Award, it combines robust build quality with easy operation and quiet performance.

## Description

Buy National Geographic Hobby Rock Tumbler Kit – Durable Leak-Proof Rock Polisher with 7-Day Timer, Complete Rock Tumbling Kit with Grit, Jewelry Settings & GemFoam Polish, Educational STEM Science Kit: Rock Tumblers - desertcart.com ✓ FREE DELIVERY possible on eligible purchases

Review: Genuine review after fully using it! - Are you wondering if it works well? It does! Any problems? None! Results? Incredible, I was truly shocked! Pros: Almost no assembly, at all. Extremely easy to understand the directions (Tumbling time will vary depending on the rocks. Don't let it scare you away when it says one phase should tumble for 6-8 days (I haven't had to tumble any that long! The longest has been 3 days). That being said, an extremely hard rock that's very jagged may need more time. Using the rocks they include, or your own collection of crystals/gemstones is a great route. A plain piece of gravel or a rock of that type is very hard and dense and may take more time (who wants polished gravel anyway though?) Extended project to do with children, lots of engagement. Because their are 4 different grit types with different purposes, the children get to return to their project, dump the rocks and check on the progress and start a new phase. It's a great opportunity to teach to teach about erosion, and show / explain what a rock looks like through millions of years of erosion and then further explain how incredible it is that we are doing this project together that mimics what nature does, we are polishing these rocks in a few weeks that takes millions of years to do in nature! It's a wonderful learning opportunity for children, as well as an extremely engaging project that although it may take quite some time for it to finish, the ongoing project itself is what makes it fun. Returning to the rocks and seeing the progress, (we actually started taking pictures each time we open it so then we can look back on the pictures and see how the rocks have changed!). I cannot say enough how great of a project this is for children to get them excited about science! Personally, I find this to be very satisfying regardless of children. This would be an extremely fun hobby for an adult as well, the above is not to say that this is a children only experience. Use or find or buy your own natural gemstones or softer rocks (look in River beds if you can!). Tumble them, polish them, and then make your jewelry or just save them to display. It's quite a satisfying feeling to see the project from beginning to end, and to know that the beautiful smooth shiny rocks were not store-bought, but that you did this with that with this machine! Cons: I've been through the tumbling process in full, twice now. I honestly cannot think of any cons at this point. It's not to say that no one has had issues, but the machine I received functions perfectly and I have had no issues with leaks or ill-fitting pieces, tearing of the belt or anything of this nature. I did take a very small amount of oil on my fingertip and lightly rub it on the belt to keep it lubricated, with the constant friction I could see how the belt can eventually wear down just like any other belt of this nature whether it's in a car or in a fan. So, keeping it very slightly lubricated will help with the health of the band. Should it break, the kid includes an extra belt and it is incredibly easy to repair, the belt is divisible and an outside piece of the equipment you simply take one off and put the other on there is no sophisticated way of connecting the belt, it is truly something my six-year-old could do with almost no instruction, so an adult will have zero issues with that! If you are interested in rock tumbling, or you just want a very fun project for your children to stimulate their interest in science or to just keep them busy using their imaginations (regarding the possibilities of what to do with the rocks, and imagining whether it will look like and the brilliant colors!) - then this is absolutely a perfect kit to start with. DO: Make sure to not put too many rocks. I've never filled mine more than one third of the way, and I wouldn't recommend doing more than that. The amount of rocks you can tumble at a time will vary depending on the size, but I also recommend not doing anything smaller than a dime because during the tumbling process it could crack and chip. I would also recommend not doing anything larger than a half dollar as well (height and width, and that'd be on the largest size). Remember, this is just the hobby edition. I do have to say though, the results are quite sophisticated for just a hobby edition! All in all, it's an excellent piece of equipment to buy if you're interested in rock tumbling but are unsure if you would stick to it or are not ready to spend a few hundred dollars on a professional Tumbler. ** I did read a few comments about the machine leaking, I have not had this problem at any point. Make sure you are putting on the inner lid correctly, as well as the top lid, then turning the black lid securing piece as tightly as possible. If you do end up having problems, I highly recommend exchanging instead of giving up, because I really have seen that it works and I just want everyone who wants to try this to have the experience I've had! It's been great fun. Wonderful purchase, no regrets!
Review: Bought for 13 year old - Amazing rock tumbler—turned rough stones into gorgeous polished gems! This tumbler is a total winner for beginners and hobbyists alike. It runs super quietly (barely noticeable even in the living room), stays cool during long cycles, and the barrel seals perfectly—no leaks or mess. I followed the standard 4-6 week process with the included grit/polish steps, and the results are stunning: dull, jagged rocks came out mirror-shiny and smooth. Easy to use and clean, the motor is strong and consistent—no stalling with a full load. Great build quality for the price—feels durable and reliable. My family loves checking the progress every week, and now we have a beautiful collection of tumbled stones for jewelry and display. If you’re into rockhounding or just want a fun, satisfying project, this is fantastic. Highly recommend!

## Features

- CREATE YOUR OWN GEMSTONES - Rock tumbling is a hugely popular hobby for kids and adults! This robust rock polisher 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.
- ALL-IN-ONE TUMBLING KIT - You get 1/2 pound of rough rocks with nine different types of gemstones inside, five jewelry fastenings, tumbler grit, a strainer, and our innovative new GemFoam polishing foam.
- USE GEMFOAM FOR DAZZLING RESULTS - This rock tumbling 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 | B086Z6ZB7R |
| Best Sellers Rank | #3,726 in Toys & Games ( See Top 100 in Toys & Games ) #366 in Educational Science Kits |
| Customer Reviews | 4.5 4.5 out of 5 stars (31,602) |
| Item Weight | 4.18 pounds |
| Item model number | NGHOBBYTUMBLER2 |
| Language | English |
| Manufacturer | JMW Sales, Inc. |
| Manufacturer recommended age | 8 years and up |
| Product Dimensions | 13.11 x 5 x 8.15 inches |
| Release date | July 5, 2023 |

## Product Details

- **Brand:** Blue Marble
- **Age Range (Description):** 8 years and up
- **Color:** Multicolor
- **Theme:** Geology
- **Item dimensions L x W x H:** 13.11 x 5 x 8.15 inches

## Images

![National Geographic Hobby Rock Tumbler Kit – Durable Leak-Proof Rock Polisher with 7-Day Timer, Complete Rock Tumbling Kit with Grit, Jewelry Settings & GemFoam Polish, Educational STEM Science Kit - Image 1](https://m.media-amazon.com/images/I/915PyUpEsJL.jpg)

## Available Options

This product comes in different **Style** options.

## Questions & Answers

**Q: What is the power consumption of this unit over a week of continuous use? (in usa on 110v). thank you.**
A: This takes .3 Amps, so (watts = amps x volts) OR watts = .3 x 110 which equals33 watts.  Now for one week would equal 33 watts x 7 days x 24 hours =5544 watts or 5.54 kilowatts for one week.At $.16 per kilowatt it comes to $.89 per week.

**Q: What the difference between this and the starter kit?**
A: There are two main differences:The Hobby Rock Tumbler has a rubber tumbling barrel with a stainless steel cap, which reduces noise and is more durable. The Starter Kit Rock Tumbler has a plastic barrel. The Hobby Rock Tumbler also has a keypad for setting the number of days you would like it to tumble, where as the Starter Kit Rock Tumbler's setting options are on/off. Thank you for your inquiry.

**Q: What pound tumbler is this product?**
A: Dearest National Geographic.... why would you only send 1# of rocks with a two pound tumbler?

**Q: Can i buy extra grit without the rocks. we have many rocks from "mining" gemstones that i would love to polish. what do you recommend?**
A: I recommend you follow the rock tumbler hobbiest MIchigan Rocks on Youtube. He's a good wealth of information for anyone getting into rock tumblers. He and other's mention that the polish from National Geographic is not good. I would go with rock tumbler polish offered by Polly Plastics.

## Customer Reviews

### ⭐⭐⭐⭐⭐ Genuine review after fully using it!
*by M***E on May 26, 2023*

Are you wondering if it works well? It does! Any problems? None! Results? Incredible, I was truly shocked! Pros: Almost no assembly, at all. Extremely easy to understand the directions (Tumbling time will vary depending on the rocks. Don't let it scare you away when it says one phase should tumble for 6-8 days (I haven't had to tumble any that long! The longest has been 3 days). That being said, an extremely hard rock that's very jagged may need more time. Using the rocks they include, or your own collection of crystals/gemstones is a great route. A plain piece of gravel or a rock of that type is very hard and dense and may take more time (who wants polished gravel anyway though?) Extended project to do with children, lots of engagement. Because their are 4 different grit types with different purposes, the children get to return to their project, dump the rocks and check on the progress and start a new phase. It's a great opportunity to teach to teach about erosion, and show / explain what a rock looks like through millions of years of erosion and then further explain how incredible it is that we are doing this project together that mimics what nature does, we are polishing these rocks in a few weeks that takes millions of years to do in nature! It's a wonderful learning opportunity for children, as well as an extremely engaging project that although it may take quite some time for it to finish, the ongoing project itself is what makes it fun. Returning to the rocks and seeing the progress, (we actually started taking pictures each time we open it so then we can look back on the pictures and see how the rocks have changed!). I cannot say enough how great of a project this is for children to get them excited about science! Personally, I find this to be very satisfying regardless of children. This would be an extremely fun hobby for an adult as well, the above is not to say that this is a children only experience. Use or find or buy your own natural gemstones or softer rocks (look in River beds if you can!). Tumble them, polish them, and then make your jewelry or just save them to display. It's quite a satisfying feeling to see the project from beginning to end, and to know that the beautiful smooth shiny rocks were not store-bought, but that you did this with that with this machine! Cons: I've been through the tumbling process in full, twice now. I honestly cannot think of any cons at this point. It's not to say that no one has had issues, but the machine I received functions perfectly and I have had no issues with leaks or ill-fitting pieces, tearing of the belt or anything of this nature. I did take a very small amount of oil on my fingertip and lightly rub it on the belt to keep it lubricated, with the constant friction I could see how the belt can eventually wear down just like any other belt of this nature whether it's in a car or in a fan. So, keeping it very slightly lubricated will help with the health of the band. Should it break, the kid includes an extra belt and it is incredibly easy to repair, the belt is divisible and an outside piece of the equipment you simply take one off and put the other on there is no sophisticated way of connecting the belt, it is truly something my six-year-old could do with almost no instruction, so an adult will have zero issues with that! If you are interested in rock tumbling, or you just want a very fun project for your children to stimulate their interest in science or to just keep them busy using their imaginations (regarding the possibilities of what to do with the rocks, and imagining whether it will look like and the brilliant colors!) - then this is absolutely a perfect kit to start with. DO: Make sure to not put too many rocks. I've never filled mine more than one third of the way, and I wouldn't recommend doing more than that. The amount of rocks you can tumble at a time will vary depending on the size, but I also recommend not doing anything smaller than a dime because during the tumbling process it could crack and chip. I would also recommend not doing anything larger than a half dollar as well (height and width, and that'd be on the largest size). Remember, this is just the hobby edition. I do have to say though, the results are quite sophisticated for just a hobby edition! All in all, it's an excellent piece of equipment to buy if you're interested in rock tumbling but are unsure if you would stick to it or are not ready to spend a few hundred dollars on a professional Tumbler. ** I did read a few comments about the machine leaking, I have not had this problem at any point. Make sure you are putting on the inner lid correctly, as well as the top lid, then turning the black lid securing piece as tightly as possible. If you do end up having problems, I highly recommend exchanging instead of giving up, because I really have seen that it works and I just want everyone who wants to try this to have the experience I've had! It's been great fun. Wonderful purchase, no regrets!

### ⭐⭐⭐⭐⭐ Bought for 13 year old
*by N***E on January 29, 2026*

Amazing rock tumbler—turned rough stones into gorgeous polished gems! This tumbler is a total winner for beginners and hobbyists alike. It runs super quietly (barely noticeable even in the living room), stays cool during long cycles, and the barrel seals perfectly—no leaks or mess. I followed the standard 4-6 week process with the included grit/polish steps, and the results are stunning: dull, jagged rocks came out mirror-shiny and smooth. Easy to use and clean, the motor is strong and consistent—no stalling with a full load. Great build quality for the price—feels durable and reliable. My family loves checking the progress every week, and now we have a beautiful collection of tumbled stones for jewelry and display. If you’re into rockhounding or just want a fun, satisfying project, this is fantastic. Highly recommend!

### ⭐⭐⭐⭐⭐ Fun product and fantastic customer service! 👏
*by J***. on January 12, 2026*

This was very easy to use. As a first-time hobbyist, I've always wanted a rock tumbler, and the instructions and suggestions were very clear and easy to follow. I started making tumbled stone jewelry as gifts for friends, family, and the steady stream of caregivers and medical professionals my husband and I see on a daily basis. We are both disabled and I (despite my own issues) am my husband's main caregiver. Rock tumbling and making jewelry have become my escape from the daily chaos of our lives, my relaxation from my anxiety and chronic pain disorders, and something I can share that is uniquely mine. I've had this tumbler for a year now, and have enjoyed it immensely. Recently, however, the belt broke. Not a big deal but, since replacing the the broken belt with the included replacement belt, the unit was fine for a couple of weeks before it suddenly stopped one night in the middle of a 7-day tumble. I tried re-seating the canister and started it again, only for it to stop again (with all of the lights flashing) 30 seconds later. I looked online for any suggestions dealing with the issue, and came up with several possible things that could be causing the problem. I removed the belt and carefully cleaned the rotating pins. I cleaned between the base rollers and the buffer pads, and made sure no pet hair or dirt was built up anywhere that could be causing the stoppage. I removed the canister and removed half of the stones in case the weight was the issue. Despite all of this, the unit would not keep spinning, and kept "freezing " within minutes of restarting. Today is Monday 1/12/26. My husband is in the hospital due to an infection, and I am trying to catch up on some things I've been putting off due to time constraints. So, I called the customer service number listed on the box. Since the product was purchased from Amazon, I was able to supply the NatGeo/BlueMarble help desk associate with the date and order number of the unit. I was also able to give them the SEC/lot number information since I still have the box. I then found out that I was 13 days past the warranty/exchange period. Some companies would simply refuse any liability because it was past the warranty date, but not this one. After hearing my issue, what I had done to address the problem, and getting the pertinent information about my purchase of the item and the unit itself, they generously offered to replace the entire kit. I was definitely not expecting that, but it was a great surprise and absolutely made my day. In conclusion, the tumbler is great for a first-time or young user. The directions are easy to follow. The stones are beautiful, if a bit small, but perfect for jewelry or other things. There is an included booklet with sample pictures to help you identify your stones, which I found very helpful. Above all, NatGeo and Blue Marble are VERY responsive to any issues and actually stand behind their product, a rare find in today's marketplace. I highly recommend this product for young or beginner tumblers. It took me until my 57th birthday to get one, and I've been having a blast!

## Frequently Bought Together

- NATIONAL GEOGRAPHIC Hobby Rock Tumbler Kit – Durable Leak-Proof Rock Polisher with 7-Day Timer – Complete Rock Tumbling Kit – Geology Hobby for Kids, Educational STEM Science Kit, Rock Collection
- 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 Ireland*
*Store origin: IE*
*Last updated: 2026-03-10*