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Why does carbon dating say diamonds are only a few thousand years old?
We have all heard of carbon dating, of course. In this article, we will take a look at how it works.
This article is in part inspired by an article I read recently claiming that carbon dating proves that diamonds mined from deep underground are in fact only a few thousand years old! We will see why that claim is incorrect later in the article.
What is carbon dating
All living things contain carbon, and most of that carbon comes from C02 in the atmosphere. Plants absorb CO2 directly from the atmosphere and convert it to carbohydrates via photosynthesis. Animals get their carbon either by eating plants or by eating other animals that (ultimately) got their carbon by eating plants. One way or another, the vast majority of carbon in living things comes from the atmosphere.
The atmosphere contains three main isotopes of carbon which we will discuss in more detail later. These are C12 which makes up about 99% of the carbon in the atmosphere, C13 which makes up about 1%, and C14 which is about one part per trillion. Since the carbon in a living organism comes from atmospheric carbon, the proportion of the three isotopes in land-based living organisms will match the proportions in the atmosphere (marine life forms are slightly different).