---
product_id: 219854530
title: "National Geographic GemFoam Reusable Rock Polisher for Rock Tumblers | Reusable Polishing Foam, Adds Shine After Grit Cycles, Rock Tumbling Media, Works with Tumbled Rocks and Minerals"
brand: "blue marble"
price: "$42.24"
currency: USD
in_stock: true
reviews_count: 12
category: "Blue Marble"
url: https://www.desertcart.us/products/219854530-national-geographic-gemfoam-reusable-rock-polisher-for-rock-tumblers-reusable
store_origin: US
region: United States of America
---

# 3-day tumbling for max shine Reusable polishing foam - up to 6 cycles Optimized for harder rocks (6+ hardness) National Geographic GemFoam Reusable Rock Polisher for Rock Tumblers | Reusable Polishing Foam, Adds Shine After Grit Cycles, Rock Tumbling Media, Works with Tumbled Rocks and Minerals

**Brand:** blue marble
**Price:** $42.24
**Availability:** ✅ In Stock

## Summary

> ✨ Elevate your rock game—shine smarter, not harder! 🪨

## Quick Answers

- **What is this?** National Geographic GemFoam Reusable Rock Polisher for Rock Tumblers | Reusable Polishing Foam, Adds Shine After Grit Cycles, Rock Tumbling Media, Works with Tumbled Rocks and Minerals by blue marble
- **How much does it cost?** $42.24 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.us](https://www.desertcart.us/products/219854530-national-geographic-gemfoam-reusable-rock-polisher-for-rock-tumblers-reusable)

## 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

- • **Eco-Smart & Reusable:** Use the same GemFoam up to 6 polishing cycles—sustainability meets sparkle.
- • **Award-Winning Quality:** From the Toy of the Year-winning Blue Marble brand, trusted for creativity and STEM learning.
- • **Unmatched Shine Boost:** Transforms dull rocks into museum-worthy gems with patent-pending foam tech.
- • **Effortless Final Polish:** Simply add after final grit cycle for a silky smooth, light-reflecting finish.
- • **Universal Compatibility:** Works seamlessly with any durable rock tumbler, especially National Geographic sets.

## Overview

The National Geographic GemFoam Reusable Rock Polisher is a cutting-edge polishing media designed to deliver superior shine to tumbled rocks. Compatible with all durable tumblers and reusable for up to six cycles, it enhances the final polish phase by smoothing and brightening harder rocks (6+ hardness) over a 3-day tumbling period. Developed by award-winning Blue Marble, this eco-friendly foam media is a must-have for hobbyists seeking professional-grade results and STEM-inspired creativity.

## Description

desertcart.com: National Geographic GemFoam Reusable Rock Polisher for Rock Tumblers | Reusable Polishing Foam, Adds Shine After Grit Cycles, Rock Tumbling Media, Works with Tumbled Rocks and Minerals : Industrial & Scientific

Review: The foam does what the step 4 grit should have done - First and foremost this review is for the foam pieces. I noticed the reviews are all mixed for different National Geographic rock tumbling products I am very pleased with the foam to use after step 4 which as others have stated left the rocks or minerals still very dull not shiny, this got the job done. Just use it after step four if you were using National Geographic grit as instructions suggest. I am also getting a better step 4 from another brand to compare that with the foam to see if it does better or the same as foam but as for now I am very pleased. Here in this photo I tumbled a chert in the foam after Nat geo 4 step. Chert is the stuff you commonly see in Some concrete It has a hardness of seven I'm thinking that at least for the foam anyway the harder the rock the better they shine like this one does quite well. I am currently tumbling a less hard rock serpentinite with hardness of four or five and it’s not getting quite as shiny but I think it’s still better than before, I am letting it tumble longer. So Basically if it’s a six or seven or harder it will shine better using these whereas step four did nothing using National Geographic. It’s cool that these rocks in the photo came from my backyard doesn’t look like something from a backyard once you shine them up like this pretty cool Update: The pictured rocks turned out amazing, however the serpentinite never got shiny. My conclusion is that these foam pieces only work for harder rocks that are somewhat smooth to begin with. The rocks in this photo were somewhat smooth to begin with but not shiny the foam without a doubt made a huge difference the light did not bounce off them like it does now also they are now silky smooth as opposed to somewhat smooth. So if you use these bear in mind they will only work for harder somewhat smoother rocks. I did use a better step 4 for my serpentine and I still see no difference so just like with the foam I think some rocks are just not going to shine as well as others. The foam still gets a five star for what it did to that chert though and you do need to go the full 3 days of tumbling because after day one I saw no results. A total of five days in the foam wouldn't hurt either I was pleased with 3 though.
Review: they work well - If you enjoy polishing rocks with a tumbler, the gem foam are a nice little trick to use to get that final polish. I have been working with rocks that are not always ideal for polishing. I use the gem foam after I burnish my stones and the gem foam helps to get that extra bit of shine out of my rocks. I cannot speak as to how many batches one can get out of the gem foam before they no longer do their job, but for the price they are worth the purchase.

## Features

- A BRAND NEW WAY TO MAKE TUMBLED ROCKS SHINE – GemFoam is a unique new rock polishing media that gives unprecedented shine to tumbled rocks. Just add the patent-pending rock polishing media to your tumbler after the final grit cycle for great results!
- A LITTLE GOES A LONG WAY – Add a pack of GemFoam to your rock tumbling arsenal and use for multiple tumbling projects. GemFoam is reusable for up to 6 rock polishing cycles and comes with a convenient reusable bag made of mesh for easy storage.
- WORKS WITH ANY ROCK POLISHER - GemFoam is safe to use with any durable tumbler. For best results, use with our National Geographic line of tumblers and rock tumbling supplies, like our ceramic media, tumbling grit, and rock refill packs.
- EASILY IMPROVE YOUR ROCK TUMBLING RESULTS - When your final rock tumbling grit cycle is complete, add GemFoam, water, and the rocks you'd like polished back to the tumbler and tumble up to 3 days. Rocks will will come out with polish and 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 | B08B7DJTCR |
| Age Range Description | 8 years and up |
| Best Sellers Rank | #1,744 in Industrial & Scientific ( See Top 100 in Industrial & Scientific ) #1 in Tumbling Media |
| Brand Name | Blue Marble |
| Color | Black |
| Customer Reviews | 4.4 out of 5 stars 644 Reviews |
| Educational Objective | STEM |
| Global Trade Identification Number | 00816448027451 |
| Included Components | GemFoam Reusable Rock Polisher Foam |
| Indoor Outdoor Usage | Indoor |
| Item Dimensions | 4.72 x 1.18 x 7.28 inches |
| Item Type Name | Rock Tumbling Media GemFoam Reusable Rock Polisher Foam |
| Manufacturer | JMW Sales, Inc. |
| Manufacturer Maximum Age (MONTHS) | 1188 |
| Manufacturer Minimum Age (MONTHS) | 96 |
| Manufacturer Part Number | NGFOMBAG |
| Material Type | Foam |
| Model Number | NGFOMBAG |
| Number of Players | 1 |
| Operation Mode | Manual |
| Power Source | Manual |
| Set Name | Single Set |
| Size | One Size |
| Sub Brand | National Geographic |
| Supported Battery Types | No batteries required |
| Theme | Rock Tumbling |
| UPC | 816448027451 |
| Unit Count | 1 Count |

## Images

![National Geographic GemFoam Reusable Rock Polisher for Rock Tumblers | Reusable Polishing Foam, Adds Shine After Grit Cycles, Rock Tumbling Media, Works with Tumbled Rocks and Minerals - Image 1](https://m.media-amazon.com/images/I/91Rp1wQXT4L.jpg)

## Available Options

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

## Customer Reviews

### ⭐⭐⭐⭐⭐ The foam does what the step 4 grit should have done
*by K***V on May 30, 2021*

First and foremost this review is for the foam pieces. I noticed the reviews are all mixed for different National Geographic rock tumbling products I am very pleased with the foam to use after step 4 which as others have stated left the rocks or minerals still very dull not shiny, this got the job done. Just use it after step four if you were using National Geographic grit as instructions suggest. I am also getting a better step 4 from another brand to compare that with the foam to see if it does better or the same as foam but as for now I am very pleased. Here in this photo I tumbled a chert in the foam after Nat geo 4 step. Chert is the stuff you commonly see in Some concrete It has a hardness of seven I'm thinking that at least for the foam anyway the harder the rock the better they shine like this one does quite well. I am currently tumbling a less hard rock serpentinite with hardness of four or five and it’s not getting quite as shiny but I think it’s still better than before, I am letting it tumble longer. So Basically if it’s a six or seven or harder it will shine better using these whereas step four did nothing using National Geographic. It’s cool that these rocks in the photo came from my backyard doesn’t look like something from a backyard once you shine them up like this pretty cool Update: The pictured rocks turned out amazing, however the serpentinite never got shiny. My conclusion is that these foam pieces only work for harder rocks that are somewhat smooth to begin with. The rocks in this photo were somewhat smooth to begin with but not shiny the foam without a doubt made a huge difference the light did not bounce off them like it does now also they are now silky smooth as opposed to somewhat smooth. So if you use these bear in mind they will only work for harder somewhat smoother rocks. I did use a better step 4 for my serpentine and I still see no difference so just like with the foam I think some rocks are just not going to shine as well as others. The foam still gets a five star for what it did to that chert though and you do need to go the full 3 days of tumbling because after day one I saw no results. A total of five days in the foam wouldn't hurt either I was pleased with 3 though.

### ⭐⭐⭐⭐⭐ they work well
*by E***N on January 27, 2021*

If you enjoy polishing rocks with a tumbler, the gem foam are a nice little trick to use to get that final polish. I have been working with rocks that are not always ideal for polishing. I use the gem foam after I burnish my stones and the gem foam helps to get that extra bit of shine out of my rocks. I cannot speak as to how many batches one can get out of the gem foam before they no longer do their job, but for the price they are worth the purchase.

### ⭐⭐⭐⭐ Okay, but they still don’t shine with a wet look.
*by M***N on February 1, 2025*

We bought these looking for another way to try to get our rocks to shine with a wet look. They make our rocks a little more smooth, but we still can’t figure out how to get the wet look on them. They are reusable, but you need to make sure you keep track of what you used them with or after because you don’t want to add grit to them. I would say they worked okay. The price was decent.

## Frequently Bought Together

- Blue Marble National Geographic Rock Tumbling Media – GemFoam Reusable Rock Polisher Foam, Use After Rock Tumbling Grit Cycles, Adds Shine to Tumbled Rocks and Minerals, Rock Tumbling Supplies
- 2 LBS Rock Tumbling Ceramic Filler Medi Rock Tumbling Ceramic Filler Media Non- Abrasive Ceramic Pellets for All Type Tumblers 3/16" X 3/8"
- 3LB Rock Tumbler Grit and Polish Refill Set, 4-Step Professional Polish Rock Tumbler Grit to Unlock Stunning Polished Stones. Ideal for National Geographic, KomeStone, and Other Polishers and Tumblers

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*Product available on Desertcart United States of America*
*Store origin: US*
*Last updated: 2026-08-09*