A diamond is a billion years old and therefore valuable.

Old does not mean valuable.

The water in the oceans is billions of years old (and indeed even older than any diamond). Yet ocean water is not so valuable. Age alone does not make anything rare or valuable, and it does not make a diamond a good investment.

Being old is different from taking a long time to grow.

A diamond that formed billions of years ago did not spend billions of years growing.

There is a difference between the period during which a crystal grew and the much longer time it could then spend just stuck in the ground.

The impression of a diamond slowly becoming more valuable with every passing year is a sales story – and a false one. Indeed diamond forms in earth very rapidly via a quenching process, as fast often as 45 minutes.

Indeed, a natural diamond formed 1000x faster than one gently grown in the lab.

Misleading Marketing by Diamond Miners

According to a U.S. ruling, the diamond mining cartel engaged in deceptive marketing by suggesting that because lab diamonds were not formed billions of years ago that they are not ‘real’ or have less value.

The National Advertising Division (NAD), a quasi-regulatory agency in the USA, objected to and reprimanded the Natural Diamond Council, now renamed to The Diamond Collective, for implying that lab-grown diamonds are not actual diamonds, something the Federal Trade Commission has said can be misleading.

The diamond miners’ marketing statements challenged by the NAD include: “The difference between a real diamond and a lab-grown diamond is simple.… A real diamond is unique and rare, formed one hundred miles below Earth’s surface up to 3 billion years ago.”

The NAD advised that “In the context of NDC’s challenged advertising, consumers may incorrectly conflate LGDs like Diamond Foundry’s with imitation diamonds like moissanite and cubic zirconia, which do not share the same physical properties as mined diamonds.”

The U.S. National Advertising Division recommended discontinuing an ad contrasting “real” diamonds formed up to 3 billion years ago with lab-grown diamonds said to lack nature’s “unique qualities.” In that context, the contrast implied lab-grown diamonds weren’t real diamonds. The ruling recommended that the Natural Diamond Council discontinue the implied claim that man-made diamonds are not "real" diamonds, and express claims that:

• "Today, there are many laboratory-grown and synthetic diamonds on the market. These are also made of carbon, but without the Earthly origins of real diamonds, they lack the unique qualities infused by nature."
• "The difference between a real diamond and a lab-grown diamond is simple . . . A real diamond is unique and rare, formed one hundred miles below earth's surface up to 3 billion years ago. Real diamonds undergo extraordinary environmental circumstances, bursting towards the earth's surface through volcanic eruptions. They are miracles of nature."