It seems likely that if life evolved to the point of civilization on a planet where carbon diamonds were not a scarce luxury resource, but rather a plentiful mineral as accessible as copper or iron ore, the unique characteristics they possess would be useful for practical purposes.

To quote from Wikipedia for the sake of simplicity:

diamond has the highest hardness and thermal conductivity of any bulk material.

I imagine that the hardness of diamonds would be useful to a young civilization for cutting, and probably as a weapon for hunting or combat with other civilizations.

But there would be challenges, as well. Unlike stone, which can be easily shaped or carved into useful shapes for tool use, the hardness of diamonds would likewise make them difficult to craft into workable shapes.

Furthermore, it seems like it would take some time before the usefulness of diamond hardness would become significant. For instance, while arrows and spears tipped with diamond come to mind, they wouldn't be of much greater use than sharpened stone for hunting or combat early on, in terms of ability to penetrate an organism's flesh.

At some point, a civilization would reach the point where the hardness of diamonds could be harnessed for practical use. In advanced modern technology, diamond tipped blades and other tools use even tiny amounts of carbon diamond for practical reasons, and that's even despite the scarcity of the resource.

In this hypothetical world, what kinds of early tools could a civilization devise from the diamonds all around them?

Note: while preparing to post this question I noticed that a similar one has been asked. At the risk of being overruled, I believe it is not a duplicate, because this question is particularly focused on how diamonds would first be used as tools by a civilization coming of age on a planet with diamond abundance.

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    $\begingroup$ Technical diamonds are neither scarce nor particularly expensive. As a very hard (but unfortunately very brittle) material diamond is already used wherever it makes sense to use it. What we cannot yet do efficiently is to exploit the high thermal conductivity of diamond and use it as a substrate for microchips. $\endgroup$
    – AlexP
    Aug 16, 2017 at 2:40
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    $\begingroup$ Have you ever played minecraft? $\endgroup$
    – JAD
    Aug 16, 2017 at 9:05
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    $\begingroup$ I understand that Diamonds are far more plentiful than thought, just that large corporations have created a false supply, to increase the price. en.wikipedia.org/wiki/Artificial_scarcity $\endgroup$ Aug 16, 2017 at 9:39

6 Answers 6


Diamonds are practically useless to primitive people

For technologically primitive peoples stone is used either because it is tough or because it can form a sharp edge. Diamond has neither property.

They cannot form a good cutting edge, because they are a crystalline solid and thus have planes of weakness, meaning it breaks in specific patterns. Those patterns do not make good cutting edges. Generally to get a sharp edge you want an amorphous glass (like obsidian). Plain old bottle glass can form an edge a hundred times sharper than any diamond.

Large diamonds would shatter if used as a hammer. Keep in mind that hard is not the same thing as strong. A stone or copper hammer can crush and shatter a diamond. Diamond is hard, but weak (brittle). A diamond hammer would not survive the first few whacks.

Diamond would not be useful to primitive people as anything other than decoration. If diamond was included as microscopic crystals in another stone it might make for a slightly better whetstone or more durable grindstone, but those will be pretty minor effects as both are generally extremely durable to begin with.

  • $\begingroup$ But can diamond spearhead or arrowhead penetrate human flesh, if it's brittle? $\endgroup$
    – Vylix
    Aug 16, 2017 at 10:42
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    $\begingroup$ Having used a milling machine where the milling bit is stupid hard, I can concur. You so much as ding it while it's stopped and the bit has a tendency to shatter. Hard isn't the same as strong indeed. $\endgroup$ Aug 16, 2017 at 11:38
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    $\begingroup$ @Vylix anything will penetrate if you throw it hard enough, but it will not penetrate anywhere near as well as a point made from flint or obsidian. A sharpened hardened wooden point may even preform better than a diamond one. $\endgroup$
    – John
    Aug 16, 2017 at 14:01

The problem with utilizing diamonds is that they are small. Even a "Large" diamond isn't large enough to be used as an arrowhead or a knife or anything like that. Diamonds are also brittle, and can be broken with a "Standard" hammer.

The uses of diamonds are great - Once you get to the appropriate technological level. You might see diamond saws and grinding wheels in mid/late 1800s, and small-scale heat transfer once computers start to show up - Somewhere between the 40s and 70s, although I would guess that it would be closer to the 60s and 70s once computers started getting smaller and heat mattered a bit more.

  • $\begingroup$ Saws were used at least as early as in ancient Egypt. And in stone age they made sword like clubs, by putting small microlith blades on it. $\endgroup$
    – Vashu
    Aug 16, 2017 at 4:02
  • $\begingroup$ If diamond were abundant, wouldn't it make sense to have a big diamond crystal? I'm not a geologist though, so I don't know if the formation process restrict the size of the diamond. $\endgroup$
    – Vylix
    Aug 16, 2017 at 10:44
  • $\begingroup$ @Vylix I have a background in Earth Science it's not about formation, the "diamonds to size of cape cod" line in the movie The Core is probably not too far off, the problem is transportation; diamonds are denser than most mantle derived melts the reason they are transported by Kimberlite magmas is that they [Kimberlites] are extremely dense but energetic so they can keep small diamonds entrained like mud in a river. $\endgroup$
    – Ash
    Aug 16, 2017 at 11:44
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    $\begingroup$ @Vashu A Diamond "Saw" is more like a grinding wheel with tiny diamonds embedded in it. Additionally, a sword in such a manner, even if you could find diamonds big enough, would be much like a hammer: The diamonds would break very quickly. $\endgroup$
    – Andon
    Aug 16, 2017 at 22:29

Firstly diamonds are thought to be extremely abundant in the Earth, just not on the surface, so what you're suggesting is simply greater transportation of existing material. Diamonds form at approximately 900km depth in the mantle and are only brought to the surface by energetic and above all dense deep mantle magmas known as Kimberlite Melts. Kimberlites have to be relatively dense for a mantle derived magmatic body to transport diamonds because diamonds are themselves extremely dense, they also have to be energetic and fast moving because they're still less dense than the diamonds and they, the diamonds, would otherwise settle out before they reached the surface and in fact that's exactly what the big ones do. Kimberlites are only exposed in terranes where there is weathering of old, deep, Precambrian and Cambrian rocks because their density precludes them reaching the surface. So to have more and larger diamonds on the surface you would need a denser, faster moving transport system (which you can't have, mantle chemistry barely allows for Kimberlites) and more deeply eroded strata which would mean pushing forwards the stone age several Geological Periods to later in the history of the world.

Now to diamond tools; diamonds have very poor shock resistance and they burn relatively easily so even if for some reason stone age man did somehow have diamonds the size of their head to work with the techniques that apply to flint and other knapped stones won't work because they're based on shock and neither will those usually applied when working bone and antler because they're based on heat. To work diamond effectively you need more diamonds of a finer size grade in a fixative to keep them where they are and present them to the piece you're working on as an abrasive. As an abrasive diamond has no equal so sand, or better yet sandstone, made entirely from diamond dust might potentially be useful in shaping more mechanically sound materials like jadeite or nephrite or argillites which take a sharp edge and work harden with use. Actually having said that I realise that diamond is actually no more useful than quartz in this context because it's not the abrasive grains but the degree of fixation into their matrix that makes them effective for smoothing and polishing. If you had large, like smartphone screen surface area large, pieces of basically flat, rough surfaced diamond they would make for perpetual sharpening stones those would be useful. I'm reasonably sure you could use basic mechanical preparation techniques to create such an object if you had a big enough diamond to start from, something basically tabular and about 2200 carats.

  • $\begingroup$ The OP seems to imply the planet isn't Earth. So if a hypothetical planet had a different chemical makeup to the Earth (i.e. much more carbon, different ratios of the other elements), couldn't it theoretically have a different mantle chemistry allowing for larger diamonds to reach the surface? $\endgroup$
    – 8DX
    Aug 16, 2017 at 13:42
  • $\begingroup$ @8DX Maybe, I'm not going to try to work that out though, it's a complex interaction between chemistry, heat, pressure, crustal thickness, mantle viscosity, plume basal depth et cetera ad nauseam. I've run the numbers just once for a three hundred level paper and they're heinously complicated even when you know the answer ahead of time. $\endgroup$
    – Ash
    Aug 16, 2017 at 14:01
  • $\begingroup$ Diamond... burns? $\endgroup$
    – Vylix
    Aug 17, 2017 at 1:57
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    $\begingroup$ @Vylix Yeah in 1772 a French scientist by the name of Antoine Lavoisier the "father of modern chemistry" burned a diamond using sunlight and a lens to prove they're pure carbon. I can't remember the auto-ignition point, it's pretty high, but they burn much more quickly in contact with a flame. $\endgroup$
    – Ash
    Aug 20, 2017 at 7:06

Jumping ahead a bit from paleolithic technology to something more like the Bronze Age, I can think of a few different uses for large, abundant diamonds.

  1. Best. Pizza stone. Ever. Diamond's very high thermal conductivity could be harnessed to make high-quality cooking implements, allowing for fast, even cooking. You would need large, flattish pieces to form the bottom of pots, pans, baking sheets, etc. Just keep them out of the very center of the fire, as diamond oxidizes at about 700°C. This would require the ability to either find or make diamonds that are fairly level and smooth.

  2. Let the sun shine in. Assuming that your civilization is able to construct enclosed buildings, diamond crystals could be used like ship deck prisms to greatly increase the amount of light inside a dwelling. This old technology is being rediscovered (using re-purposed bottles instead of glass prisms) to light homes in places where electricity is prohibitively expensive. This would not require much if any processing of the diamond crystals; even heavily included, irregular chunks would work, though clearer, more regular and polished pieces would be more effective. Pieces of diamond that are large and clear enough could even be used as windows or peep-holes.

  3. Better than good intentions. Once your civilization starts to feel the need for more durable roadways, diamonds could be employed as an early paving material. A pitched road, made up of large chunks buried so that the flat surface of the diamond is up, would require minimal processing.


I'm going to loosen the definition of tool a bit here, and argue that money is a tool to make exchanging goods and services easier. Other answers cover well why diamond can't be used as a physical tool like a hammer, and why it requires a lot of technology before you can use them industrially as today.

However, since they are abundant, and long lasting, attractive to humans, I'd wager they'd be a candidate for early forms of currency. A currency must have at least these 4 traits to be viable:

(paraphrased from the above link)

  1. Must not be a gas
  2. Must not be corrosive or chemically reactive
  3. Must not be radioactive
  4. Rare enough to be valuable, but not so rare that you can't find it

Diamonds meet that qualification fairly well, and indeed in our world they are a decent store of value, although the artificial control of supply mentioned elsewhere on this question and invention of more convenient forms of money (paper notes, credit cards) make them not the greatest anymore. In any case, for early humans just forming civilization and requiring a physical currency to facilitate exchange, more plentiful and easily accessible diamonds make them a contender with gold as a medium of currency.


Diamonds are very, very brittle. They are known to shatter, even in the small sizes we have on Earth. They are also very difficult to polish to a fine edge.

However, they are an EXCELLENT cutting tool. A 'large' diamond, if it shatters in just the right way, could be a decent scalpel-sized blade, which would be pretty useful for processing meat or foods. You wouldn't want to use it against any harder material or even woods, because it might shatter. Pulverized diamond would also be great for carving. Look up how the Egyptians cut through hard rock - they poured sand into a crack, then used a blunt stone to rub that sand. Sand is hard and sharp, so it cuts through the stone - that's why we have sandpaper and it's called sandpaper (we now use better compounds in it, but sand would still work). Diamonds would be even better at this.

So, there would be more stone buildings, and it would be easier to carve that stone to a higher quality.

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    $\begingroup$ "could be a decent scalpel-sized blade" - except it could not. Diamond does not break in a way that creates cutting edge, and sharpening them is possible, but difficult. Diamond knives were invented in 1955 - this late due to sharpening problems, mostly. $\endgroup$
    – Mołot
    Oct 22, 2017 at 20:01

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