For generations, diamond stood as a symbol of certainty — the hardest, most enduring substance humanity had named and measured. Yet a laser experiment has quietly undone one of materials science's most confident assumptions, revealing that diamond's melting point sits more than a thousand degrees above where the scientific consensus had long placed it. The error, born of older methods rather than careless minds, is a reminder that even the most settled knowledge remains provisional — and that new instruments have a way of humbling old certainties.