How to Make a Synthetic Diamond




About: (Is there a word that means more than "ultimate"? Oh well, I'l just make one up... "omnilent") Omnilently creative, MrCrumley fights a daily battle to save the world in his capacity as a multimedia superhe...

My 10-year Wedding Anniversary is coming up so I thought I'd make my wife something special. A few months back I'd seen a show on TV where they demonstrated how companies were now making "cultured" diamonds in the lab. There are a few different methods, but the simplest is something called "chemical vapor distillation". The process is pretty straightforward. Basically, microwaves are used to create a slurry of graphite plasma which, when rapidly cooled form a crystal structure.

I checked around on the internet and found several sites where others have been doing the same thing. The best part was that everything I'd need were pretty common household items. So, I rounded up the necessary supplies and began imagining how great life would be once I'd cornered the international diamond market.

Step 1: Materials

Here's the surprisingly short list of materials I used:

A standard home microwave oven
2 coffee mugs
3 pieces of 3mm graphite pencil lead
A few drops of extra virgin olive oil
A 5" piece of 100% cotton thread

The hardest item to find was the 100% cotton thread. It's amazing how scarce that stuff is. After searching through all of our sewing notions, I finally found some black thread that I think my mom bought back in the 70's.

Step 2: Prepare the Olive Oil

As I mentioned above, the theory behind this project is using microwaves to heat the graphite into a plasma. In general, pencil graphite is not reactive enough to microwaves. So, a thin oil is used to concentrate the heat in a specific area of the graphite. Also, as the oil heats up and begins to burn, it chemically separates the binder in the pencil lead from the graphite.

Place a few drops of olive oil onto a plate and lay the thread in the oil. The thread will absorb some of the oil.

Step 3: Transfer Oil to the Graphite

Lift the oily thread and tie a knot in it.

Don't pull the knot all-the-way closed!

Carefully slip a piece of graphite through the knot loop and lay both the thread and graphite on a plate. I used two halves of a toothpick to keep the graphite suspended above the plate. This helps keep the oil confined to a single spot on the graphite.

Pull both ends of the thread until the knot has closed around the graphite.

Wait about 30 minutes for the oil to soak into the graphite.

Step 4: Setup (i.e. Clean) the Microwave Oven

I didn't really tell my wife what I was up to. (It is, after all, a surprise.) But when she saw that it involved our microwave, her response was, "please don't burn the house down."

I assured her it wouldn't, and that I'd need to clean the microwave before my "experiment." This ended her objections.

So, while the oil was soaking into the graphite, I cleaned the microwave. The sites I'd read from others folks doing this insisted that a clean microwave would yield better results. Maybe, maybe not, but it sure looks better.

Step 5: Remove the Thread

Clip off part of the thread as close to graphite as possible. Then, gently tug on the other end of the thread and pull the knot undone.

Try not to slide the thread up-and-down the graphite. Remember, it's important to keep the oil concentrated in one spot.

Step 6: Set the Graphite on the "Crucible"

Here's the ingenious part of the project. Turn one of the coffee mugs upside-down. (I used a slightly larger one as the base.)

Set 2 more pieces of graphite (non-oiled) on the upturned mug, parallel to each other.

Lay the oiled graphite across the other 2 pieces.

Place the other coffee mug over all of it.

Presto! It's a makeshift crucible!

Step 7: Place "Crucible" in Microwave

Place the stacked mugs into the microwave. In my setup, the large bottom mug required that I remove the glass tray.

Step 8: Start the Microwave

Set the microwave for its maximum cook time at the maximum power setting. In my case, that was 99 minutes and 99 seconds - which turned out to be long enough.

Be advised: the microwave will spark a bit where the oil has soaked into the graphite. This is normal as the oil is bonding with the binder in the pencil lead. It should stop sparking after a few minutes.

After the microwave is done, let the mugs cool completely before removing them. Remember, if done correctly, you've generated 1,200+ degrees inside the crucible. Be safe.

Step 9: Admire the Finished Product

After the mugs have completely cooled, remove them from the microwave.

The oiled graphite will be broken. The others should largely be intact. You'll also find a small lump, slightly larger than a grain of sand where the oiled section was placed.

Congratulations! This is the product of your labors, a genuine diamond.

I took the raw diamond to a jeweler I know and had her test it. She confirmed that underneath the scale material, there's a tiny bit of diamond material. She said that its quality was pretty poor, but it did fluoresce like a "real" diamond.

Now, admittedly, this homemade synthetic diamond is too small and too filled with inclusions to make into jewelry. But, it technically qualifies as a diamond... and I made it, so that's pretty cool.

Step 10: Make It Into a Keepsake

Obviously, this falls a bit short of what we think of when we hear "diamond". But, after posting the original article, I came up with a pretty cool way to preserve my achievement.

I filled a small washer with clear epoxy and dropped my diamond into it. After it hardened, I strung it on a chain to make a diamond necklace.

My wife was impressed. After all, how many women can wear a diamond that their husband actually MADE?



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    395 Discussions


    Question 1 year ago on Step 1

    do you have to use 100% cotton thread or can you use regular thread


    9 years ago on Step 9

    I don't like being "that guy" but it seems there are plenty of others on this site so im going to say it anyway; thats not a diamond. Here are a few reasons why.
    1. The pencil lead you used contains a large amount of clay, not just graphite.
    2. Microwaves are not capable of generating the heat neccesary to recrystalize carbon.
    3. Even if the microwave could reach the neccessary temperature, the pressure required to make a diamond is around 50,000 to 70,000 times that of earth's atmosphere.
    4. How is it that you claim to have made a diamond in your microwave if diamonds weren't even synthesized until 1953, six years after the first microwave oven was made? If they had the technology in 1947, why not use it then?

    Sorry for pooping your party, but it looks like im not the only one.

    16 replies

    Reply 1 year ago

    so wrong. its vapor deposition, not a deep-earth tandori. doubters need to study & research more. diamond is a specific allotrope of carbon regardless of where/how it is created.


    Reply 3 years ago

    Wow way to rain on his parade man, he worked hard on that. Are you some kind of Diamond expert have you even been in a Diamond mine?


    Reply 3 years ago

    um................ maybe because they did not know how to


    Reply 9 years ago on Step 9

    Let me bomb your party.

    1. A real diamond placed in a CO2 atmosphere will dissolve into "nothing"--no pressure or heat involved.

    2. Fake industrial diamond is not manufactured under such high temperatures or pressures either.

    3. An Australian high-school student developed a way of coating materials in diamond micro-dust, using COLD and low pressures--great for making grinding wheels but hopeless for laser focusing devices.

    Superheat and pressure is only theory.


    Reply 3 years ago

    Do you even know what Diamonds are?

    1) If diamonds dissolved when introduced to a C02 atmosphere then there would be no practical way to handle nor create them.

    2) 'Fake' or cultured gem-Diamonds of the 21st century are manufactured by either CVD or HPHT (Chemical Vapor Deposition or, High Pressure, High Temperature respectively) CVD is used to produced 'Gem' Quality Diamonds en masse at an increased albeit profitable expense. HPHT is used to create diamonds for industrial use, this is a rather old method it operates very efficiently.

    3) You can make 'diamond' micro dust with borax and Pipe cleaners. Arguing nomenclature is fruitless but the point being, diamonds are assigned arbitrary value and significance.

    4) His method is crude, but it follows procedure. Graphite is used to cause a reaction between a Hydrocarbon (like methane) and atomic hydrogen once the latter is turned into a gas which then should bond with the Hydrocarbon and then once it dissipates you have a Diamond. For a gem quality diamond to be produced you need to have a temperature range of 900 - 1200 degrees celsius.


    Reply 9 years ago on Step 9

    And let me party on your bombing: You're not the first person to point this out.


    Reply 9 years ago on Step 9

    I was bombing Cheathum14, not you. But I do re-assert that extreme heat and pressure will not be the methods by which "gem" quality diamonds are reproduced--and even then they won't be "gem" quality because they will lack the unique flaws of the natural product.

    Of course, if subsequently worthless "pure" diamond can be grown then lenses and other optics will take a massive left turn in efficiency. And yes, I confidently predict that such method will not only validly suck carbon out of the atmosphere, it will turn out rocks in such volume that the South African economy will collapse.


    Reply 8 years ago on Introduction

    Synthetic diamonds are made at about 300deg C, but usually in a pressure vessel using microwave radiation and a "seeding" crystal. You can make diamond as big or small as you want by growing them in a chemically neutral environment (nobel gas/ nitrogen) using CO2. Check out wikipedia, has an article about them. The diamonds are purer than natural sourced diamonds, and are currently being applied to electronics, especially light based circuits.
    Go to a big jewelers and ask for yellow diamonds- they are tinted to distinguish them natural ones, but they can come in any colour depending on the material you poison the crystals with. They have the same colour as urine.
    I haven't tried it, so can't say if this will work, but I'm skeptical of the chemistry.Once I've destroyed my microwave (it's crap anyway), i'll let you know. (^^)


    Reply 4 years ago on Introduction

    Synthetic diamon can be made on 2 method:

    - CVD (chemical vapor deposition)

    - HTHP (high temperatures - high pressure)

    Read more about Grown diamond made on CVD process. You can watch video:


    Reply 8 years ago on Introduction

    I think I've mentioned this before, but I haven't read if it's been tried: perhaps a greater pressure could be achieved by incorporating a vice in the process... and maybe a tiny (yet strong) person to crank it - just an idea.

    Synthetic diamon can be made on 2 method:

    - CVD (chemical vapor deposition)

    - HTHP (high temperatures - high pressure)


    Reply 5 years ago on Introduction

    You can make industrial daimounds with TNT. Does that mean that they started doing so in 1863.


    Reply 8 years ago on Step 9

    It isn't only theory, graphite is the most stable allotrope of carbon at ambient temperature and 1atm pressure. (Yes you can convert diamond into graphite in an inert atmosphere at around 1000°C) Maybe there are some ways that don't need ultra high temperatures or pressures, but it is proven that diamond is more stable than graphite at these conditions and thats why it transforms into it.


    Reply 9 years ago on Step 9

    You didn't quite bomb my party. I know that diamonds can be formed at much lower temperatures and pressure.(Microscopic diamonds can form on the surface of the sun where the temp. is only 10,000 and where there is little pressure) I was just saying that for a diamond of that size (visible to the naked eye) to be formed, it would take more than the pressure and heat a microwave can generate. Also, if i'm wrong, so be it, i'm only a sophomore in high school anyway and i'm taking physics next year.