The "lead" in your pencil is misnamed. The gray stuff is actually composed of graphite, which is the stablest form of the element carbon. Its bonded atoms are arranged in planar sheets, layered on top—and aside—each other. Which explains why your pencil lead is soft: Those single-atomed planar sheets ("graphene" in the singular) can glide against each other with ease.
You know what's also made out of carbon, though? Diamonds. The objects that are celebrated for their hardness. Diamonds' strength comes from the fact that their carbon atoms are bonded in all directions; that chemical three-dimensionality is what makes them not just beautiful, but useful for industrial applications.
Here's the question, though: Can you take the atoms in graphene and rearrange them into diamonds? In theory, you definitely could. Given graphene's stability, you would need to subject it to around 150,000 times the atmospheric pressure at the Earth's surface. Which is ... impractical.
A team of researchers at Stanford's SUNCAT Center for Interface Science and Catalysis say they've found another way to control the structural transition between carbon atoms—at the nanoscale. The team started with a platinum support, and loaded it with several sheets of graphene. Then, they added hydrogen atoms to the topmost layer. Their finding? The hydrogen binding that ensued started, essentially, a domino effect among the atoms: Structural changes started at the top of the sample, but spread to the carbon layers underneath. And those changes transformed the carbon sheets into a new arrangement of carbon atoms—an arrangement that resembles, yep, a diamond.
This was, it's worth noting, something of an accidental discovery: The researchers were initially testing whether the addition of hydrogen would change the chemical properties of graphene in a way that would make it useable in transistors. Instead, they learned something else that could prove useful for the material sciences. The "diamonds" that result from the hydrogenation process aren't the kind you'll find at Zales (sorry, guys); they could be the kind, though, that could prove useful in industrial applications like cutting blades and electrochemical sensors. And they're the kind that offer hope to the would-be Rumpelstiltskins of the world: You may not be able to turn straw into gold, but you can, it seems, turn a pencil into a diamond.