Single review
4M Crystal Growing Kit Review
Reviewed from the manufacturer's published specifications and the arithmetic on them. We have not used it, and we say so.
By Sawyer V. · Published
The short answer
The 4M Crystal Growing Experiment Kit publishes 7 crystal-growing experiments using 3 bags of crystal compound and 3 bags of seeding mixture, with a stirring bowl and spoon, 7 display bases, 7 covers and 7 ring templates, rated 10 years and up. Each result takes days, not minutes.
Block & Beaker earns a commission when you buy through our links, at no cost to you. It never changes a ranking, and we say so plainly when the right answer is the cheaper set, or nothing at all. Full disclosure · How we pick.
At a glance
The picks, ranked
Tap any row to jump to the full reasoning. Prices come live from Amazon where we have them and read “check price” where we don’t — never a number we cannot stand behind today.
| # | Product | Best for | Price |
|---|---|---|---|
| 1 | The product 4M Crystal Growing Experiment Kit Seven genuine crystal specimens with display cases, if the household can leave them undisturbed. | Ten and up, for a child who can wait a week for a result | |
| 2 | The one that keeps going NATIONAL GEOGRAPHIC Mega Science Lab 45 in-kit experiments plus 85+ household ones, and it includes crystal growth too. | Eight and up, for breadth and a bonus guide that never expires | |
| 3 | The other patience purchase NATIONAL GEOGRAPHIC Hobby Rock Tumbler Kit Four grits and nine gemstone types, and afterwards it polishes free rocks. | Eight and up, where the machine outlives the supplies | |
| — | Not the same subject Thames & Kosmos Chemistry C500 Shelved nearby at a similar age rating, and it is a chemistry course rather than a craft. | Ten and up, for real chemistry |
4 picks, including 1 we tell you to skip. Ages shown are the manufacturer’s own rating, not ours.
What we can tell you, and what we cannot
We have not grown these crystals. No lab, no samples, no test children, no star rating here or in the structured data.
Published contents, experiment counts and timescales we can report. How large the crystals actually get, and whether they survive being handled, we cannot.
The specification that decides it
The arithmetic
4M Crystal Growing Experiment Kit, published
| Experiments | 7 |
|---|---|
| Crystal compound | 3 bags |
| Seeding mixture | 3 bags |
| Display | 7 bases, 7 covers, 7 ring templates |
| Also included | Stirring bowl and spoon |
| Stated age | 10 years and up |
| Time per experiment | Days, not minutes |
| Consumables | Yes — the compound is the whole product |
What the numbers mean in practice
Days per result is the real specification. Crystals grow on their own schedule and nothing speeds them up. A child expecting a result on the afternoon the kit is opened will be disappointed, and an adult who has not read this will be surprised too.
Undisturbed is a hard requirement. A growing crystal needs a surface nobody clears, for days. In a household with no spare shelf this is the constraint that decides whether the kit works at all.
Seven display cases is what makes waiting worthwhile. The payoff is a keepable object. Without the cases these would be seven things that get knocked over.
10+ is about care rather than danger. The published rating reflects following a multi-day procedure precisely, which is genuinely beyond most younger children.
Worth knowing before you buy
Crystal-growing compounds are chemicals and the published rating is 10 and up. Keep the bags away from younger siblings, and do not let a finished crystal be treated as a sweet — they can look remarkably like one.
Who should skip it
An impatient child. This is the least immediate purchase on this site. If a result today matters, buy geodes or a logic game.
A household with no undisturbed surface. Seven experiments each needing days of stillness is a real demand on a small home.
Anyone wanting the main present. Seven results and then it is finished. It is a good second gift and a poor headline one.
Say the unwelcome thing
Do not buy this expecting a science course
The kit grows crystals. It does not teach a syllabus, and the instruction material is proportionate to that.
If the child wants to understand why crystals form rather than to have seven of them, a chemistry set with a real manual is the better purchase — see chemistry sets.
Where it sits
The crystal kit appears in science experiment kits and in rock and geology kits.
In full
Every pick, and what is wrong with it
Published specifications only, each linked back to the page it came from. Where a manufacturer publishes nothing, the row says so — we do not fill blanks in.
1. The product
4M Crystal Growing Experiment Kit
4M · 5557 · maker rates it 10+
Seven genuine crystal specimens with display cases, if the household can leave them undisturbed.
- Experiments
- 7 crystal-growing experiments
- Contents
- 3 bags of crystal compound, 3 bags of seeding mixture, stirring bowl and spoon, 7 display bases, 7 display covers, 7 ring templates
- Stated age
- 10 years and up
- Consumables
- Yes — the compound is the whole product
4M publishes 7 crystal-growing experiments with 3 bags of crystal compound and 3 bags of seeding mixture, a stirring bowl and spoon, 7 display bases, 7 display covers and 7 ring templates, rated 10 years and up, with each experiment taking days rather than minutes.
The display components are a real part of the value and get overlooked. Seven bases, covers and ring templates mean the results are keepable objects rather than something that gets thrown away, which is what makes a slow experiment feel worth the wait.
The honest arithmetic is that this is seven results spread across several weeks, and then it is finished. That is a perfectly good thing to buy as long as it is what you meant to buy.
Replay signal
- Open-ended or one-shot
- One-shot, seven times over
- Does anything run out
- Definitively. Three bags of compound, and when they are gone the kit is a set of display cases
Why we say so: 4M publishes three bags of crystal compound across seven experiments. That is the arithmetic that decides this purchase: it is seven results, spread over weeks because crystals take days to grow, and then it is finished. Excellent as an event; poor as the main present.
What’s wrong with it
Three bags of compound is the whole product. When they are gone, it is a set of display cases.
| Experiments | 7 crystal-growing experiments |
|---|---|
| Contents | 3 bags of crystal compound, 3 bags of seeding mixture, stirring bowl and spoon, 7 display bases, 7 display covers, 7 ring templates |
| Stated age | 10 years and up |
| Consumables | Yes — the compound is the whole product |
| Time per experiment | Days, not minutes — crystals grow on their own schedule |
Every figure above is from 4M, Crystal Growing Experiment Kit. Blanks are shown as “not published” rather than filled in.
2. The one that keeps going
NATIONAL GEOGRAPHIC Mega Science Lab
National Geographic · Mega Science Lab · maker rates it 8+
45 in-kit experiments plus 85+ household ones, and it includes crystal growth too.
- Experiments in the kit
- 45, across chemistry, earth science and science magic
- Bonus guide
- 85+ further experiments using household items, for 130+ in total
- Includes
- Volcano build, glow-in-the-dark crystal growth, and the tools for both
- Stated age
- 8+
National Geographic publishes 45 in-kit experiments across chemistry, earth science and science magic, a volcano build and glow-in-the-dark crystal growth, plus a bonus guide of 85+ experiments using household items, rated 8+.
If crystals are the appeal but the buyer wants more than seven results, this covers the same ground inside a much broader kit.
Replay signal
- Open-ended or one-shot
- Guided, and the 45 in-kit experiments end. The 85 household ones do not
- Does anything run out
- The supplied materials run out; the household half of the book never does
- Room to grow
- The bonus guide is the genuinely durable part, and it costs the manufacturer almost nothing to include
- Adult required
- Supervision for the chemistry third; the earth science and household experiments are largely self-run
Why we say so: National Geographic publishes 45 in-kit experiments plus a bonus guide of 85+ using household items. That second number is why this kit outlasts most of its price band: roughly two-thirds of the published content needs nothing but a kitchen.
What’s wrong with it
Its in-kit chemicals also run out; only the household half is durable.
| Experiments in the kit | 45, across chemistry, earth science and science magic |
|---|---|
| Bonus guide | 85+ further experiments using household items, for 130+ in total |
| Includes | Volcano build, glow-in-the-dark crystal growth, and the tools for both |
| Stated age | 8+ |
| Consumables | Yes — the supplied chemicals and crystal compounds are used up |
Every figure above is from National Geographic toys, Mega Science Lab. Blanks are shown as “not published” rather than filled in.
3. The other patience purchase
NATIONAL GEOGRAPHIC Hobby Rock Tumbler Kit
National Geographic · Hobby Rock Tumbler · maker rates it 8+
Four grits and nine gemstone types, and afterwards it polishes free rocks.
- Includes
- Tumbler, four polishing grits, sifter, learning guide
- Rough gemstones
- Nine types
- Barrel
- Noise-reducing, leak-proof, stainless steel lid
- Controls
- One-touch settings with an automatic shutoff timer
National Geographic publishes a tumbler with four polishing grits, nine rough gemstone types, a sifter, a noise-reducing barrel and an automatic shutoff timer, rated 8+.
Both teach that some results take days. The tumbler keeps working afterwards on rocks that cost nothing; the crystal kit does not.
Replay signal
- Open-ended or one-shot
- Semi-open: the machine is permanent, the grit is not, and rocks from a beach are free
- Does anything run out
- The grits and the supplied gemstones run out; refill grit is sold separately
- Room to grow
- Once the supplied rough is gone, the tumbler works on anything the child collects
- Adult required
- For loading and for the timer; the tumbling itself is unattended
Why we say so: National Geographic publishes four polishing grits, nine gemstone types and an automatic shutoff timer. The machine outliving the grit is what makes this different from a one-shot geology kit — but it runs for days per batch, so it is a patience purchase, not an afternoon one.
What’s wrong with it
Runs for days per batch and refill grit is sold separately.
| Includes | Tumbler, four polishing grits, sifter, learning guide |
|---|---|
| Rough gemstones | Nine types |
| Barrel | Noise-reducing, leak-proof, stainless steel lid |
| Controls | One-touch settings with an automatic shutoff timer |
| Extras | Jewelry fastenings for the polished stones |
| Stated age | 8+ |
| Consumables | Yes — the four grits and the supplied rough are used up |
Every figure above is from National Geographic toys, Hobby Rock Tumbler Kit. Blanks are shown as “not published” rather than filled in.
Skip this one
Thames & Kosmos Chemistry C500
Thames & Kosmos · 665012 · maker rates it 10+
Shelved nearby at a similar age rating, and it is a chemistry course rather than a craft.
- Experiments
- 28
- Manual
- 48 pages
- Chemicals included
- 5
- Equipment
- Safety glasses, test tubes, dropper pipettes, double-headed measuring spoon
Thames & Kosmos publishes 28 experiments, a 48-page manual and five chemicals with safety glasses, test tubes and dropper pipettes, rated 10 years and up, stating compliance with EN 71-4.
Both are rated 10+ and they are different products. The C500 teaches chemistry with a manual and requires supervision; this grows attractive objects with minimal instruction. A buyer who wants the former will find seven crystals thin.
Replay signal
- Open-ended or one-shot
- Guided, not open-ended: 28 experiments, then the manual is finished
- Does anything run out
- Yes — the chemicals are consumed, and Thames & Kosmos sells replacements
- Room to grow
- Steps up to the larger C1000, C2000 and C3000 sets in the same line
- Adult required
- The maker rates it 10+ and it involves real chemicals
Why we say so: Thames & Kosmos publishes 28 experiments, a 48-page manual and five chemicals. Five finite chemicals across 28 experiments is arithmetic, not opinion — this set has an end, and it is better to know that before Boxing Day than after.
What’s wrong with it
Five chemicals across 28 experiments, and an adult is assumed.
| Experiments | 28 |
|---|---|
| Manual | 48 pages |
| Chemicals included | 5 |
| Equipment | Safety glasses, test tubes, dropper pipettes, double-headed measuring spoon |
| Stated age | 10 years and up |
| Batteries | 1 x 9V (not included) |
| Consumables | Yes — the five chemicals are used up |
Every figure above is from Thames & Kosmos, Chemistry C500. Blanks are shown as “not published” rather than filled in.
We are not putting a buy button on this one. It is easy enough to find if you want it anyway — but we would rather send you to something that gets played with twice.
Questions people actually ask
Frequently asked
How long do 4M crystals take to grow?
Days rather than minutes, per experiment. 4M publishes seven experiments and crystals grow on their own schedule — nothing speeds them up. The kit needs a surface that stays undisturbed for the duration, which is the practical constraint most buyers do not plan for.
How many crystals can you grow with the 4M kit?
Seven experiments, from three bags of crystal compound and three bags of seeding mixture, with seven display bases, covers and ring templates supplied. When the compound is gone the kit is a set of display cases.
What age is the 4M crystal growing kit for?
4M publishes 10 years and up. The rating is about care and precision rather than danger — following a multi-day procedure accurately is genuinely beyond most younger children, and an inaccurate mix simply does not crystallize.
Is the 4M crystal kit worth buying?
As a second gift for a patient child, yes — seven keepable specimens in display cases is a real outcome. As the main present, no. It produces nothing on the day it is opened and finishes after seven results. Science experiment kits.
Sources
Where these figures came from
Every specification on this page traces to one of these. If a manufacturer publishes nothing on a point, the page says so rather than filling the gap.
Read next
Where to go from here
Back to Reviews, or read how we pick.