Summary (tl;dr)

Recent scientific breakthroughs have revealed unexpected melting behavior of diamonds under extreme pressure, challenging long-held theories and holding significant implications for the future of fusion energy. Concurrently, the broader diamond market is experiencing a major shift due to the rise of lab-grown diamonds, which are also produced under extreme conditions and are profoundly impacting the traditional natural diamond industry.

Essential Background

For decades, scientists have strived to understand the fundamental properties of carbon, particularly how diamond, its hardest known form, behaves under the immense pressures and temperatures found deep within planets or in inertial confinement fusion experiments. Previous theoretical models and experimental data regarding diamond's melting point and structural transitions under extreme conditions had a persistent mismatch, creating a 20-year scientific puzzle. Traditional diamond production, whether natural or synthetic, involves subjecting carbon to extreme pressure and heat, but directly observing the melting of diamond at such extremes remained challenging.

The Full Story

New research, conducted at facilities like the Lawrence Livermore National Laboratory and the University of Rochester's Laboratory for Laser Energetics, has recently provided groundbreaking insights into how diamonds melt under extreme pressure. Scientists discovered that, surprisingly, solid diamond can be less dense than the liquid carbon it melts into, a characteristic similar to how ice floats on water. This unexpected behavior, observed under pressures millions of times greater than Earth's atmospheric pressure, also confirmed that diamond retains its familiar cubic crystal structure right up until it melts, rather than transforming into a predicted new solid phase. This research effectively resolves a two-decade-long discrepancy between experimental results and theoretical predictions for diamond's melting behavior at extreme pressures. Additionally, international collaborations, including those involving the University of Rostock and the European XFEL, have successfully studied liquid carbon directly for the first time, further narrowing down its true melting point and revealing diamond-like structures within the liquid state.

Why It Matters

These discoveries are crucial for advancing our understanding of materials science and planetary physics, as the behavior of carbon under extreme conditions is vital for modeling the interiors of carbon-rich exoplanets. More immediately, the findings have profound implications for inertial confinement fusion, a promising clean energy technology. The research suggests that using slightly slower initial shocks in fusion implosions could still fully melt diamond fuel capsules, potentially tripling the energy yield. This could accelerate the development of sustainable fusion power, presenting massive long-term business and financial opportunities. In a related but distinct trend in the business and finance sector, the diamond industry is currently facing significant disruption. Natural diamond prices have plummeted by approximately 50% over the past four years, primarily driven by advancements in lab-grown diamond technology. Lab-grown diamonds, which are physically and chemically identical to natural diamonds and often produced under extreme pressure and temperature, are considerably cheaper and are rapidly gaining market share, fundamentally reshaping the economics of the diamond market.

Geographic Location

• Lawrence Livermore National Laboratory, Livermore, Alameda County, California, United States (scientific research on diamond melting and extreme pressure physics)
• University of Rochester's Laboratory for Laser Energetics, Rochester, Monroe County, New York, United States (scientific research on diamond melting using powerful lasers)
• European XFEL, Schenefeld, Pinneberg District, Schleswig-Holstein, Germany (research on liquid carbon using X-ray lasers)
• University of Rostock, Rostock, Mecklenburg-Vorpommern, Germany (collaboration on liquid carbon research)
• Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden, Saxony, Germany (collaboration on liquid carbon research)