World's oldest diamonds – Quick facts

Diamonds are formed deep within the Earth and it takes a lot of time (usually few billion years) for diamonds to be formed. The formation of diamonds does not only require extremely large period of time it also requires extremely high temperatures and extremely high pressure. Synthetic diamonds also need these conditions just like natural diamonds do, the only differences between these two is the place of their creation (lab compared to deep within the Earth), and of course the factor of time.

Some diamonds are extremely old, even older than 3 billion years. Currently the world's oldest diamonds are 4 billion years old diamonds found trapped inside zircon crystals from the Jack Hills region, few hundreds kilometers north of the Western Australian capital Perth, so diamonds are basically almost as old as our planet is.

These world's oldest diamonds were discovered by Australian and German scientists within the zircon grains. This discovery supports the theory that Earth in the Hadean era (about 4.4 billion years ago) was not a "warm as hell" zone but was significantly cooler which enabled creation of these diamonds. These diamonds are about 1 billion years older than the oldest known diamonds found in terrestrial rock. And so the Australian diamonds currently hold the "world's oldest diamonds" title. At least for time being.

Not all diamonds on our planet were formed under these conditions. Some of them were a result of meteorite strike. These diamonds are usually extremely small, and are called nanodiamonds or microdiamonds.

How do diamonds come up to the surface? The answer is volcanoes, or to be more precise volcanic pipes that carry diamonds together with magma depositing them near to surface. Without this process diamonds couldn't be mined but of course not all volcanoes carry diamonds with them to the surface so natural diamonds are therefore quite rare, and of course quite expensive.