What is the typical age range for most natural diamonds?

• A. Most natural diamonds crystallized within the last 100 million years.
• B. Diamonds form continuously and are all younger than 500 million years.
• C. Diamonds crystallize around 500 million years ago.
• D. Most natural diamonds crystallized well over a billion years ago, commonly around 1 to 3 billion years old.

Answer: (D)

Diamonds form deep in the Earth's mantle under high pressure, so their creation happens over very long timescales. Dating studies of diamond inclusions and related minerals show that the vast majority crystallized billions of years ago, typically in the range of about 1 to 3 billion years ago. This places most natural diamonds in the Archean to early Proterozoic eras, reflecting the long, stable conditions of the deep mantle during those times. While a few diamonds can be younger or older, the common pattern is a deep‑mantle origin well over a billion years ago, around 1–3 Ga. The other statements imply much younger ages or a single mid-point age, which contradicts radiometric dating evidence and the mantle's long history of diamond formation.