Carbon in Cremated Ashes Explained by Carbon Scientists, Inorganic Chemists, and Forensic PhDs

A question we’re often asked: “Is there enough Carbon in ashes after cremation to use for the diamond process?” The answer is, “Yes, absolutely!”

A lot of Carbon burns off during cremation, but not to worry, there is still plenty of Carbon left in ashes - mostly in the form of compounds called Carbonates.

In this article, we’ll draw from expert research published by Carbon scientists, inorganic chemists, and forensic PhDs to explain the exact chemistry and science behind the Carbon left in ashes, as this is their domain of expertise (once a diamond is formed, we move into the world of gemologists, who are experts in the evaluation of stones).

In each section, we’ll give you the in-depth science and documented research, and then summarize it in more layman terms so you can understand all this science in simple terms.

Here’s what we’ll cover:

The biology of the human body

What happens when a body is cremated?

How Carbon is stored in ashes

Purification of Carbonates into graphite

Growing diamonds from personal Carbon

Biology of the human body

There are a total of 92 unique elements found in the human body, with each contributing to the makeup of our bodies in its own way. However, only 11 elements are found in a considerable quantity (more than 0.01%). Of those 11 primary elements making up the composition of the human body, there are 4 key elements that can be considered the essential make up for the human body.

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Source: Arizona State University Chemistry Department

The 4 elements that make up 96.2% of the average person are:

Because our body is about 60% water (H2O), Oxygen and Hydrogen play a pivotal role in our total make up. Carbon and Nitrogen are each major players in the formation of DNA, and Carbon in particular can be found throughout the body in various bonded compounds helping to form our bones, muscle tissue, major organs, skin and even hair.

Carbon in particular can be found throughout the body in various bonded compounds helping to form our bones, muscle tissue, major organs, skin and even hair.

The reason for Carbon’s leading role in the makeup of all organic life, has to do with the 4 bonds available in every Carbon atom. It’s important to note that none of these elements shown below are found freely within the body but rather bonded together to form compounds. (Source)

Carbon, being the primary building block in all organic life, exists in our bodies in a wide variety of compounds. This can vary from the well known Carbon-Dioxide (C-O2) or Methane (C2-H4) to less known terms like Calcium Carbonate (C-Ca-O3) or Carboxylic Acid (C-O-O-H). Each of these compounds serves its own purpose within the body and each compound varies in the amount of energy required to break its bonds.

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*Molecular Structure of various Carbon compounds (source: Eterneva)

Put simply (TLDR)

Human bodies are nearly 1/5th Carbon, and most of that Carbon is bound to other things like Oxygen, Hydrogen and Calcium. It’s a good thing - because if it was just Carbon-alone, we’d be 1/5th black coal! Carbon is so important in all life that we have a branch of chemistry which JUST covers molecules with Carbon in them called Organic Chemistry!

What happens when a body is cremated?

Cremation as a funeral service has existed and been in practice dating back over 17,000 years ago. While it has been used throughout history as an alternate method to burials and has ranged in popularity throughout our history depending on time period and region of the world, recently cremation has gained high popularity across the globe and particularly in the United States.

Here in the United States the cremation regulations vary state by state in terms of standard temperature and duration. Depending on the state, temperatures may range from 1,400°F to 1,800°F while internal conditions are monitored constantly to determine when cremation is complete based on a person to person basis (Source). After cremation, the body is reduced to primarily skeletal remains and base elements which are crushed into powder. The typical cremation will result in 3-7lbs of remains composed of bone fragment and powderized ashes in the form of a white to light grey powder.

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Source: Eterneva

Carbon in Ashes

After undergoing the cremation process of 1,400°F to 1,800°F the amount of remaining carbon is greatly reduced from 18.5% to roughly 2-4% due to much of the Carbon being burned off in the form of Carbon Dioxide that exits the cremation chamber.

The remaining Carbon is primarily in the form of Carbonate compounds such as Calcium Carbonate that remains in bones. A Carbonate is, by definition, “a polyatomic anion with the formula CO3 which consists of a Carbon atom surrounded by three Oxygen atoms” (Source). These Carbonates have a much higher bond strength than weaker Carbon based compounds prevalent in hair and muscle tissue. In addition, bones can act as thermal insulators for Carbon prevalent in bone marrow and other tissues that may not reach the heat required to decompose the available Carbon depending on the cremation conditions and duration of time held at the given temperature. This can result in elemental Carbon being found present within bone fragments even after high heat cremation.

“After cremation, elemental Carbon can be found within bone fragments, even after high heat cremation, the bone insulates the Carbon from combustion. The remaining 2-4% Carbon is found in Calcium Carbonates, the building blocks for bones.”

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* Elemental Carbon found in the inside of a bone post-cremation (source: Eterneva)

The existence of residual Carbonates in cremated remains was validated by a study conducted in 2009 by the Department of Biology and Department of Anthropology at Ludwig-Maximilian-University Munich which was later published by Forensic Science International in January of 2011 (Source).

In this study, the researchers collected cremated remains from a modern crematory for analysis. In addition, the researchers used a cow tibia bone as a stand-in for human remains and cremated the bones with ranging temperatures from 100°C to 1,000°C (212°F to 1,832°F) to compare the reduction of the remaining Carbonates as temperature was increased.

This study was conducted with the intention of showing genetic DNA testing could be used on cremated remains for the use of forensic analysis in criminal cases. Each piece of bone used in the study was held at the control temperature for one and a half hours and then analysed to see the resulting elemental analysis of the samples as a function of increasing cremation temperature. What the researchers found was that there were residual Carbonates remaining in the test samples and cremated remains all the way up to the maximum temperature above 1,800°F.

“There is residual Carbonates all the way up to the maximum cremation legal temperatures above 1,800°F.” - Forensic Science International

Put simply (TLDR)

Even though the Carbon from most of the body is burned off during cremation, lots of the Carbon wrapped up in the Calcium compounds (which helps give your bone strength) is still there after cremation, in a form called Calcium Carbonate. On average, there is 2-4% Carbon left in ashes after cremation in two forms:

  1. Elemental Carbon: found inside the bone
  2. Calcium Carbonate: the Carbon compound that makes up bones

How are Ashes Tested for Carbon

Carbon testing is a very common practice and is used for many different purposes and industries.

The most widely known sort of Carbon testing is the type used for Carbon dating, which is how scientists can determine the age of rocks, fossils, and even Wooly Mammoths found trapped in ice!

However, Total Carbon analysis (‘TC’ for short) is a test used for much more common industries like pharmaceuticals, microelectronics, oil and gas, and even forensics.

Choosing the right type of testing can be very important when it comes to Carbon since some common elemental testing methods cannot detect Carbon at all.

For instance, Atomic Emissions Spectroscopy is very commonly used for analysis of metals. However, the testing procedure typically calls for mixing Carbon graphite with the test sample in order to burn the elements for spectral analysis, therefore making it impossible to test for innate Carbon within the sample itself.

When it comes to Total Carbon analysis, there are methods that scientists have developed to test specifically for both organic and inorganic Carbon. These techniques use an Oxygen rich controlled environment where the sample is combusted (burned) with a quartz heating element.

This allows for testing to proceed without adding any extra fuels, or additives that could contaminate the testing sample. After combustion in the controlled chamber, Carbon combines with Oxygen to create Carbon Dioxide (C02), which is then analyzed with an infrared detector to determine the quantity of Carbon in the sample.

Eterneva has used this technique on samples of cremated ashes, hair, and even aquamation ashes to determine the range of Carbon percentage we can expect from each.

All testing was performed on controlled samples at TDI-Brooks International/B&B Laboratories Inc. In fact, they pretty much wrote the book on total Carbon testing [(Source)] (https://www.tdi-bi.com/analytical_services/environmental/NOAA_methods/TOC.pdf).

Here are the results of the testing:

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TLDR (Put Simply)

Testing for Total Carbon means testing for the amount of Carbon in the sample in two different basic types of compounds: organic and inorganic. Add those together and you get (surprise!) Total Carbon, or TC. The results above are from 2 cremation remains (one from 20 years ago and one from a recent cremation), one hair sample, and one Aquamation sample (eco-friendly cremation). Turns out hair is more than a third Carbon!

Reduction of Carbonates to Pure Graphite

While Carbon exists in the molecular form of a Carbonate compound, Carbonates must first be decomposed using a high heat reduction process in order to purify cremated remains to the useful form of Carbon graphite (the personal Carbon used in a memorial diamond).

This process uses an extremely high temperature low Oxygen controlled environment. Some common methods use specially selected gases such as Chlorine to generate gases from the impurities in the ashes and Carbonates that have low melting points. According to Allah D Jara in her review of Purification, application and market trend of natural graphite, published in September 2019 in the International Journal of Mining Science and Technology (Source), “The purification efficiency of this method is known to be high, reaching more than 98%.”

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Source: Eterneva

In order to further increase the purity of the personal graphite we must use a second “high-temperature method, where the graphite is heated to more than 4892 °C where the impurities with low boiling point become vaporized and removed. Thus, the purity of graphite becomes more than 99.995%. These methods require highly specialized infrastructure and equipment along with high level expertise but are capable of reducing organic and inorganic materials containing Carbonates and free form Carbon to the commonly used crystalline graphite powder.

It’s a complex, multi-stage process requiring weeks of work to purify cremated remains into graphite that’s more than 99.995% pure graphite that can be used in diamond synthesis.

Put simply (TLDR)

Thanks to chemistry, we can get the Carbon out of the Calcium Carbonate by heating it so it breaks down. By using gases like Chlorine instead of air, the Carbon is separated from the other parts of the molecule, leaving just the Carbon.

Growing Diamonds from Personal Carbon

The use of High Pressure High Temperature (HPHT) technology to grow diamonds in a lab originated in the 1950’s and was pioneered in the United States by General Electric. While the origins in the technology were centered on industrial application, the capability to grow jewelry grade diamonds has advanced greatly in recent years. As of the early 1990’s lab grown diamonds have been produced with increasing size and quality that can be compared to typical natural diamonds used in common jewelry practices.

In general, HPHT growth proceeds at temperatures and pressures designed to approximate the conditions of natural diamond growth. According to research by Shirley and Sigley published on the Gemological Institute of America’s website, within the earth, diamonds generally form at pressures of 5.5–8.0 GPa (roughly the weight of a commercial jet plane balanced on a finger tip) and temperatures of 1,800–2,500°F (Source).

The main principle of HPHT diamond growth uses a Carbon graphite powder placed into a growth cell as the Carbon source that grows into diamond under the immense pressures and temperatures.

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Source: Eterneva

The other primary components of an HPHT growth cell are a metal alloy (usually composed of Iron, Nickel, and Aluminum) which helps to facilitate diamond growth at a lower temperature than that required in nature, along with a small diamond seed the size of a grain of sand that functions as the diamond formation site that the Carbon can attach to as a starting point for the lab grown diamonds.

“A memorial diamond is a mix of personal Carbon and generic Carbon that crystalizes around a tiny diamond seed to form a beautiful diamond from a remarkable person.”

When growing a memorial diamond, the personal Carbon derived from a person’s cremated ashes is used in the same HPHT process described above. By mixing someone’s personal Carbon with some of the generic Carbon (personal Carbon usually makes up 10-15% of the diamond), the same HPHT technology can be used to create a diamond of equal quality that holds significant meaning to that person’s loved ones that reaches far beyond just the normal beauty of a piece of jewelry.

Put simply (TLDR)

Carbon is an amazing material – it can join to itself in lots of different ways. We usually see it in a form called graphite, which is in pencil leads, or in Carbon fiber. In a small range of very high heat and really high pressure, it joins together into a crystal form – diamond!

The machines used to create those pressures and temperatures are called HPHT machines (‘High Pressure, High Temperature’ – scientists love to shorten things…) and come in a few different types, some of which are HUGE and used to make rough diamond for things like cutting tools, and some of which are about the size of your household refrigerator. Because we’re growing totally unique and very special diamonds using very special personal Carbon, we use smaller, more precise HPHT machines.

Sources

  1. Elemental Composition of the human body:
    https://askabiologist.asu.edu/content/atoms-life
  2. Bonds and Compounds in the body:
    https://www.rsc.org/Education/Teachers/Resources/cfb/basicchemistry.htm
  3. Cremation Practices:
    https://www.cremationresource.org/cremation/how-is-a-body-cremated.html
  4. Carbonates-Chemistry LibreTexts:
    https://chem.libretexts.org/Bookshelves/Inorganic_Chemistry/Supplemental_Modules_(Inorganic_Chemistry)/Descriptive_Chemistry/Main_Group_Reactions/Compounds/Carbonates
  5. Research potential and limitations of trace analyses of cremated remains:
    https://www.sciencedirect.com/science/article/pii/S0379073810002860?via%3Dihub
  6. Purification, application and current market trend of natural graphite:
    https://www.sciencedirect.com/science/article/pii/S2095268618304269
  7. Observations on HPHT Diamond Growth:
    https://www.gia.edu/gems-gemology/fall-2017-observations-hpht-grown-synthetic-diamonds
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