We research products independently. When you buy through links on this page, we may earn a commission from Amazon at no extra cost to you. As an Amazon Associate we earn from qualifying purchases. Learn more.
Rock tumbler grit does all the actual work in a rock tumbler. The motor just turns the barrel. Pick the wrong sequence, skimp on the dose, or let one coarse grain sneak into your polish, and a month of tumbling ends in dull stones.
The good news: grit isn't brand-specific, and the standard sequence is well established. This guide covers which sizes to use at each stage, how much to add, and which grit kits give you the best value for your barrel size. Every kit's contents below come from the maker's or retailer's listing.
Quick Picks
- Best Overall: KoolStone Rock Tumbler Grit and Tumbling Media Kit 10 lb. Best for regular tumblers who want bulk grit, labeled sizes and media in one box.
- Best Brand-Name Kit: Lortone Rock Tumbler 4-Stage Grit Pack. Best for a classic 60/90 to aluminum oxide sequence from a legacy brand.
- Best Mid-Size Refill: National Geographic Rock Tumbler Grit and Polish Refill Kit. Best for kit tumbler owners who process up to 20 lb of rock.
- Best with Ceramic Media: National Geographic Rock Tumbler Grit & Media Refill Kit. Best for small batches that need media to fill the barrel.
- Best Single Batch: Rockhound's 1st Choice Rock Tumbler Refill Grit Kit. Best for one 3 lb batch with the stages clearly sized.
- Best with Plastic Pellets: Dan&Darci Rock Tumbler Grit Refill Kit 3.5 lb. Best for budget kits and cushioning in the polish stage.
- Best Polish Upgrade: JESCO Cerium Oxide Rock Polish 1 lb. Best for chasing a higher shine on quartz-family stones.
Rock Tumbler Grit Comparison Table
| Kit | Best for | Stage sizes / materials | Grit amount | Media | Rock covered (maker's claim) |
|---|---|---|---|---|---|
| KoolStone 10 lb | Overall | 60 SiC, 150 SiC, 600 SiC, 1200 aluminum oxide | 2 + 2 + 1.5 + 1.5 lb | 2 lb ceramic, 1 lb plastic | Up to 70 lb |
| Lortone 4-Stage Grit Pack | Brand-name | 60/90 SiC, 150/220 SiC, 500+ aluminum oxide, aluminum oxide polish | 16 + 14 + 12 + 12 oz | None | Up to 12 lb |
| NatGeo Grit and Polish Refill | Mid-size | 4 stages, silicon carbide | Not itemized | None | Up to 20 lb |
| NatGeo Grit & Media Refill | Ceramic media | 4 stages, silicon carbide | Not itemized | 1.5 lb ceramic, GemFoam | 8 to 10 lb |
| Rockhound's 1st Choice | Single batch | 60/90 SiC, 120/220 SiC, 500 aluminum oxide, 1200 aluminum oxide | 3 + 3 + 1.5 + 1.5 oz | None | Up to 3 lb |
| Dan&Darci 3.5 lb | Plastic pellets | Coarse, medium, pre-polish, polish | 1 + 1 + 1/2 + 1/2 lb | 1/2 lb plastic pellets | Not stated |
| JESCO Cerium Oxide | Polish upgrade | Cerium oxide | 1 lb | None | Polish stage only |
The 4-stage grit sequence
-
1
Coarse
60/90
- Material
- Silicon carbide
- Job
- Rounds edges, removes pits and cracks
- Time (Mohs 7)
- 7 to 10 days, often repeated
- Done when
- Rounded, no pits or sharp edges
- Dose
- 4 tbsp
-
2
Medium
120/220 or 150/220
- Material
- Silicon carbide
- Job
- Removes coarse scratches
- Time (Mohs 7)
- About 7 days
- Done when
- Even, smooth matte surface
- Dose
- 4 tbsp
-
3
Pre-polish
500 to 600
- Material
- Silicon carbide or aluminum oxide
- Job
- Removes fine scratches
- Time (Mohs 7)
- About 7 days
- Done when
- Faint sheen when dry
- Dose
- 4 tbsp
-
4
Polish
Oxide polish
- Material
- Aluminum oxide, cerium oxide or tin oxide
- Job
- Brings out the shine
- Time (Mohs 7)
- 5 to 7 days
- Done when
- Looks the same wet and dry
- Dose
- 4 tbsp
Grit sizes and stage times: Lortone, Kingsley North and Harbor Freight manuals (times for stones around Mohs 7). Doses: Lortone's published grit chart; per-pound cross-check from Rocktumbler.com. Grit isn't brand-specific: any coarse-to-fine sequence works if you don't skip a stage.
The Best Rock Tumbler Grit Kits, Reviewed
KoolStone Rock Tumbler Grit and Tumbling Media Kit 10 lb: Best Overall
Who it's for: anyone running batches regularly, in any brand of rotary tumbler.
This is the best value among the kits we found, and one of the few that tells you exactly what's inside. You get 2 lb of 60 grit silicon carbide, 2 lb of 150 grit silicon carbide, 1.5 lb of 600 grit silicon carbide, and 1.5 lb of 1200 grit aluminum oxide polish. It also includes 2 lb of ceramic media and 1 lb of plastic pellets. KoolStone says it covers up to 70 lb of rock across multiple batches.
The sequence is sound: a real coarse grit, a medium, a 600 pre-polish, and a fine aluminum oxide polish. KoolStone's dosing guidance (about 2 tablespoons per pound of stone, 7 to 10 days per step) lines up with mainstream practice. Including both ceramic and plastic media saves you a separate order. KomeStone sells a near-identical 10 lb kit if that's what's in stock.
Pros
- Labeled grit sizes for every stage
- Ceramic and plastic media included
- Low cost per pound of rock
- Works in any rotary tumbler
Cons
- Too much for someone with one small kit tumbler
- No extra-coarse grit for very angular rough
- Bulk bags need dry storage
KoolStone Rock Tumbler Grit and Tumbling Media Kit 10 lb
by KoolStone
Lortone Rock Tumbler 4-Stage Grit Pack: Best Brand-Name Kit
Who it's for: owners of Lortone and other hobby-grade tumblers who want a classic, proven sequence.
Lortone's pack follows the sequence its manuals teach. You get 16 oz of 60/90 silicon carbide, 14 oz of 150/220 silicon carbide, 12 oz of 500+ aluminum oxide pre-polish, and 12 oz of fine aluminum oxide polish. Lortone rates it for up to 12 lb of rock. That's four batches in a 3 lb barrel or one full run in a 12 lb barrel.
Using aluminum oxide for both pre-polish and polish is a hallmark of Lortone's method, and it suits the quartz-family stones most people tumble. The pack carries a California Proposition 65 warning for crystalline silica, a reminder to pour grit gently and avoid breathing the dust.
Pros
- Matches Lortone's published instructions
- Aluminum oxide pre-polish and polish
- Good size for 3 to 4 batches in 3 lb barrels
- Legacy brand with consistent sizing
Cons
- Higher cost per pound than bulk kits
- No media included
- Retailers sometimes substitute other brands when stock is short
Lortone Rock Tumbler 4-Stage Grit Pack
by Lortone
Amazon availability: Lortone's 4-Stage Grit Pack showed as currently unavailable on Amazon.com when we checked in October 2026, and Lortone sells mainly through lapidary dealers. If you'd rather order on Amazon, the National Geographic Rock Tumbler Grit and Polish Refill Kit is a four-stage alternative sold by Amazon; National Geographic rates it for up to 20 lb of rock and says it works in any tumbler. It's reviewed on this page.
National Geographic Rock Tumbler Grit and Polish Refill Kit: Best Mid-Size Refill
Who it's for: owners of National Geographic and other kit tumblers who want a no-fuss refill.
This refill covers four stages (coarse, medium, pre-polish and polish) in screw-top containers, with a 10 mL measuring scoop and instructions. National Geographic says it polishes up to 20 lb of rock and works with any tumbler. That's a lot of batches in a 2 lb kit barrel.
The containers are the quiet win. Bags spill and absorb moisture; screw-top tubs keep stages separate and dry. The downside is that the listing doesn't give mesh sizes or per-stage weights, so you can't compare it precisely against other kits.
Pros
- Enough for many small-barrel batches
- Screw-top containers and a scoop
- Works in any tumbler
- Simple, labeled stages
Cons
- Mesh sizes not published
- Per-stage weights not itemized
- No media
National Geographic Rock Tumbler Grit and Polish Refill Kit
by National Geographic
National Geographic Rock Tumbler Grit & Media Refill Kit: Best with Ceramic Media
Who it's for: small-batch tumblers who often run short of rock to fill the barrel.
This version pairs four stages of silicon carbide grit with 1.5 lb of ceramic pellets, 30 g of GemFoam, and a 10 mL scoop. National Geographic rates it for 8 to 10 lb of rock.
Ceramic media is the reason to choose it. In a 1 to 3 lb barrel, you rarely have enough good rough to hit the recommended fill level. Ceramic pellets take up the slack, cushion the stones, and carry grit into pits and crevices. GemFoam is National Geographic's reusable polishing foam for a final run after the polish stage.
Pros
- 1.5 lb ceramic media included
- GemFoam for a final shine run
- Good fit for kit tumblers
- Includes a measuring scoop
Cons
- Covers fewer pounds of rock than the plain refill
- Mesh sizes not published
- GemFoam is a brand-specific extra, not a substitute for proper polish
National Geographic Rock Tumbler Grit & Media Refill Kit
by National Geographic
Rockhound's 1st Choice Rock Tumbler Refill Grit Kit: Best Single Batch
Who it's for: first-timers who want exactly one batch with no leftovers, or anyone testing a new rock type.
This kit is built for one 3 lb batch, and every stage is labeled. You get 3 oz of 60/90 black silicon carbide, 3 oz of 120/220 black silicon carbide, 1.5 oz of 500 aluminum oxide pre-polish, and 1.5 oz of 1200 white fused aluminum oxide polish (rated 1.5 micron or finer). The maker markets it for Thumler's, Lortone, National Geographic and other tumblers.
It's an expensive way to buy grit per pound, but it's the easiest way to run a test batch right. Note that pellets are not included.
Pros
- Pre-portioned for one 3 lb batch
- Every grit size labeled
- Fine 1200 aluminum oxide polish
- Good for testing a new stone
Cons
- Highest cost per pound of rock
- No media
- Not enough for a repeated coarse stage
Rockhound's 1st Choice Rock Tumbler Refill Grit Kit
by Rockhound's 1st Choice
Dan&Darci Rock Tumbler Grit Refill Kit 3.5 lb: Best with Plastic Pellets
Who it's for: owners of small kit tumblers who want a refill plus cushioning pellets.
Dan&Darci packs 1 lb of coarse grit, 1 lb of medium, 1/2 lb of pre-polish and 1/2 lb of final polish, plus 1/2 lb of polypropylene plastic pellets. The extra coarse and medium grit is the right weighting, because those stages do most of the work and often need repeating.
Plastic pellets are lighter than ceramic. They cushion stones in the polish stage, which helps prevent fresh chips on nearly finished stones, but they do little grinding. Dan&Darci doesn't publish mesh sizes, so match stages by name only.
Pros
- Extra coarse and medium grit
- Plastic pellets for the polish stage
- Works with any brand
- Budget-friendly
Cons
- Mesh sizes not listed
- No rock-capacity claim
- Plastic pellets don't help grinding the way ceramic does
Dan&Darci Rock Tumbler Grit Refill Kit 3.5 lb
by Dan&Darci
JESCO Cerium Oxide Rock Polish 1 lb: Best Polish Upgrade
Who it's for: hobbyists whose stones come out smooth but not glassy, and who want to try a different final polish.
Most kits finish with aluminum oxide. Cerium oxide is the other classic final polish, widely used on quartz-family stones and glass. JESCO sells it in a 1 lb container, which goes a long way, since polish is used in tablespoons per batch.
A word of honesty: a dull finish is far more often caused by contamination, a rushed pre-polish, or chipped stones than by the polish itself. Fix those first. Then a cerium oxide run is worth trying, especially on agate and sea glass. We go deeper in our upcoming guide to rock polishing compounds.
Pros
- Classic polish for quartz-family stones and glass
- 1 lb lasts many batches
- Pairs with any grit kit
Cons
- Polish stage only
- Won't fix problems from earlier stages
- Not needed if your aluminum oxide polish already works
JESCO Cerium Oxide Rock Polish 1 lb
by JESCO
Rock Tumbler Grit Buying Guide
Grit Sizes by Stage
Grit numbers are mesh sizes: the lower the number, the coarser the particle. Most published sequences look like this.
| Stage | Typical grit | Material | What it does |
|---|---|---|---|
| 1. Coarse | 60/90 (some kits use 60 or 80) | Silicon carbide | Rounds edges, removes pits and rough spots |
| 2. Medium | 120/220 or 150/220 | Silicon carbide | Removes coarse scratches, leaves a smooth matte surface |
| 3. Pre-polish | 500 to 600 | Silicon carbide or aluminum oxide | Removes fine scratches, starts a faint sheen |
| 4. Polish | Fine aluminum oxide (e.g., 1200 or TXP), cerium oxide or tin oxide | Oxide polish | Produces the glassy shine |
Manufacturers vary in the details. Lortone's manuals use 60/90 and 120/220 silicon carbide, then aluminum oxide pre-polish and polish. Kingsley North's rotary instructions use 80, 220 and 600 grit, then cerium oxide. Rocktumbler.com sells a 60/90, 150/220, 500F and TXP aluminum oxide sequence. Any of these works if you go coarse to fine and don't skip a stage. Our step-by-step rock tumbling guide explains each stage, and our rock tumbling timeline calculator shows how long each one takes.
How Much Grit to Use
Dose by barrel size. Here's Lortone's published chart, in level tablespoons:
| Barrel | 60/90 | 120/220 | Pre-polish | Polish |
|---|---|---|---|---|
| 1.5 lb | 2 to 4 | 2 to 4 | 3 to 5 | 3 to 5 |
| 3 lb | 4 | 4 | 4 to 6 (6 in the 3A manual) | 4 to 6 (6 in the 3A manual) |
| 6 lb | 10 | 10 | 12 | 12 |
| 12 lb | 20 | 20 | 24 | 24 |
Rocktumbler.com recommends about 2 level tablespoons per pound of rock in a rotary tumbler and 1/2 tablespoon per pound in a vibratory. Either method works. More grit is not better beyond these levels, because excess just thickens the slurry.
Silicon Carbide vs Aluminum Oxide vs Cerium Oxide
Silicon carbide is extremely hard (about 9 to 9.5 on the Mohs scale) and fractures into sharp edges, so it cuts fast. That's why it handles the grinding stages. Aluminum oxide is slightly softer and more uniform, which makes it the standard pre-polish and polish in many kits. Cerium oxide and tin oxide are final polishes prized for quartz-family stones and glass. Kits that include one oxide polish are fine for most rocks. Still need a machine? See our best rock tumbler picks.
Extra Coarse Grit for Big Barrels
If your rough is very angular, a coarser grit speeds things up. Rocktumbler.com sells 46/70 extra coarse grit but recommends it only for barrels of 6 lb or more. In smaller barrels, repeat the 60/90 stage instead.
Media: Ceramic vs Plastic
Ceramic media is dense, so it grinds alongside your rocks, fills empty space, and pushes grit into crevices. Many hobbyists leave it in for every stage; KomeStone says to keep its ceramic in for all stages. Plastic pellets are light and mainly cushion stones during the pre-polish, polish and burnish stages. Kingsley North's instructions use plastic pellets to bring the barrel up to 2/3 to 3/4 full in the later stages. More in our upcoming guide to ceramic media for rock tumbling.
Keep Stages Clean
The most common reason for a dull finish is contamination. A few coarse grains carried into the polish stage leave scratches. Rinse stones, barrel and lid thoroughly between stages, scrub the lid's seal, and keep polish containers closed. Lortone's manuals also stress cleaning rocks and barrel parts with mild soap and water. If your stones still come out dull, see our rock tumbler troubleshooting guide.
Disposal and Safety
Never pour slurry down a drain. Lortone warns against it, and Kingsley North notes that slurry settles in pipes and hardens. Let it dry and bin it, or bury it outdoors. Pour dry grit gently to avoid raising dust; Lortone's pack carries a Proposition 65 warning for crystalline silica.
How We Chose
We didn't test these grit kits ourselves. We researched them. We compared the contents each maker publishes (grit sizes, materials, weights, media and rock capacity) against the procedures in Lortone's manuals, Kingsley North's rotary instructions and Rocktumbler.com's grit guidance. We favored kits that label their grit sizes, include media, and cover realistic batch sizes, and we flagged where makers leave sizes out.
FAQ
What grit sizes do I need for a rock tumbler?
A standard rotary sequence is 60/90 silicon carbide (coarse), 120/220 or 150/220 silicon carbide (medium), a 500 to 600 pre-polish, and a fine polish such as aluminum oxide or cerium oxide. Lortone's instructions use 60/90, 120/220, then aluminum oxide pre-polish and polish.
How much grit do I put in a rock tumbler?
Lortone's 3A manual calls for 4 level tablespoons of each grinding grit and 6 of each polish in a 3 lb barrel, and 10 and 12 tablespoons in a 6 lb barrel. Rocktumbler.com recommends about 2 level tablespoons per pound of rock in a rotary tumbler.
Can you reuse rock tumbler grit?
Not really. Grit breaks down into finer particles as it works, and that is part of how each stage smooths the stone. Once a stage is done, the slurry is spent. Discard it in the trash, never down a drain.
What is the difference between silicon carbide and aluminum oxide grit?
Silicon carbide is very hard and sharp, so it cuts fast and is used for the coarse, medium and often pre-polish stages. Aluminum oxide is used mainly for pre-polish and polish because it produces a finer, more even finish.
Can I use any brand of grit in my tumbler?
Yes. Grit isn't tumbler-specific; National Geographic, KoolStone and Dan&Darci all market their refills for any brand. What matters is following a coarse-to-fine sequence and not mixing stages.
Do I need ceramic media with grit?
It's not required but it helps, especially when you're short on rock. Media fills the barrel to the right level, cushions stones and carries grit into crevices. Several kits, including KoolStone's 10 lb kit and National Geographic's Grit & Media refill, include it.
Verdict
For most people, the KoolStone 10 lb kit is the best rock tumbler grit buy: labeled sizes, ceramic and plastic media, and enough for many batches. Choose Lortone's 4-Stage Grit Pack for a proven brand-name sequence. Buy Rockhound's 1st Choice when you only need one perfect 3 lb batch.