Chapter 37: Diamond and Graphite
Friday's Transfiguration lesson began with beetles.
Professor McGonagall had moved them beyond matches and needles. Turning something living into something inanimate demanded a cleaner intent and far more precision. Most of the class discovered this immediately. Beetles skittered across desks, wings buzzed in small, angry bursts, and every few seconds a student's attempt ended in a soft poof of failure.
Regulus lifted one beetle from its jar and held it steady in his palm.
He raised his wand and spoke the incantation under his breath.
The beetle stiffened. The sheen of its shell darkened from brown to a smooth, polished black. Its legs drew inward, its body shrinking and flattening as if pressed by an invisible weight. Three seconds later, an exquisite button lay in his hand, glossy and neat, with fine spiral patterns that still carried a suggestion of the beetle's original texture.
It looked better than the example on the board.
He did not ask the sort of questions he used to. Not today.
Regulus had long since noticed McGonagall's caution, and he had no interest in poking at it for sport. Silence was often the more practical choice.
McGonagall paused at his desk. She picked up the button, examined it closely, and the stern line of her mouth softened by the smallest degree.
"Mr. Black. A perfect transformation. Five points to Slytherin."
She set it down and continued her rounds, robes whispering over the stone floor.
Regulus began packing when the last student filed out. McGonagall's voice stopped him before he reached the door.
"Mr. Black, remain a moment."
When the classroom emptied, she walked to his desk. Behind her spectacles, her gaze was sharp enough to feel like a wand tip.
"Your talent for Transfiguration is exceptional," she said. "Far beyond most young witches and wizards your age."
"Thank you, Professor."
"I have noticed that lately," McGonagall continued, tone level, "you have asked fewer questions in class."
Regulus felt a faint flicker of surprise. He had assumed they would both leave the subject untouched.
"Yes, Professor."
He chose honesty, the kind that could not be used against him.
"I reflected on what you said before. At this stage, I should build a solid foundation and master the course content, rather than reaching too early for problems beyond my current level."
McGonagall studied him for several seconds, weighing sincerity the way she weighed spellwork.
At last, she gave a slight nod.
"A solid foundation is vital."
Then she added, more evenly than warmly, but not unkindly either.
"However, if you do have valuable questions, questions grounded in what we are studying and properly considered, my office door remains open."
She folded her hands on the edge of the desk.
"Hogwarts encourages thinking, Mr. Black. But thinking must be supported by knowledge."
"I understand, Professor. Thank you."
Regulus bowed with precise politeness and left.
As he walked away, he found himself thinking.
She had said it plainly. Well considered questions were welcome.
There was no reason to pretend he had none.
That afternoon, after Herbology, Regulus went straight to the Transfiguration professor's office.
He knocked. At her permission, he entered.
McGonagall sat behind her desk, marking parchment with a quill. When she saw him, the severity in her brow eased by a fraction, as though his presence was expected now that she had invited it.
She gestured to the chair.
"Mr. Black. You have a question."
"Yes, Professor. About Transfiguration. About matter."
He opened his bag and drew out two items wrapped in soft cloth, laying them on her desk with care.
A piece of graphite, dark grey and smooth, soft enough to leave marks on parchment.
A small diamond, cut and brilliant, catching candlelight and throwing it back like sparks.
"I would like to ask about these two substances," Regulus said, voice controlled and respectful.
"In some perspectives, graphite and diamond are extremely close at the most fundamental level. They originate from the same basic element."
He did not over explain. McGonagall's intelligence did not require padding.
"They look nothing alike. Their hardness, lustre, and value are worlds apart. But in the eyes of a Transfiguration master, is there an inherent similarity, or a possibility of conversion between them?"
He paused, then continued with the part that mattered most.
"I attempted to explore the connection by Transfiguration. Transforming graphite into diamond, and diamond into graphite."
His gaze remained steady.
"It is difficult. It consumes a great deal of magic, and it is hard to stabilise. It feels like more than shape and texture. It feels deeper, as if the internal structure itself resists being rewritten."
Regulus knew the true explanation in terms McGonagall would not use. Atom arrangement, bond orientation, structural lattice.
He only wanted the wizarding interpretation. The Transfiguration logic. The way a master perceived this problem through magic.
McGonagall's eyes brightened behind her spectacles. Surprise crossed her face, quickly replaced by interest.
"A profound question," she said, and there was unmistakable approval in her voice. "And an unusual one for a first year."
She looked from graphite to diamond, as if weighing them by sight alone.
"Few students ever think about Transfiguration from the perspective of fundamental relationships between substances," she went on. "Most learn match to needle, beetle to button, and focus only on form and function."
She picked up the graphite first, rubbing it lightly between her fingertips, then examined the diamond with the same careful attention.
"In my own practice," she said slowly, "different materials do have different magical manifestations."
Her tone turned instructive, clean and precise.
"Turning a feather into iron is far more difficult than turning iron into a feather, because the former requires you to create a tighter, more stable structure."
She set the graphite down.
"These two. They are opposites in appearance, yet you are correct that they share a common origin."
She did not claim certainty she did not have.
"I have not studied this specific relationship in detail. But to magical perception, a diamond feels condensed, ordered, and extraordinarily stable."
Her fingertip tapped the graphite.
"Graphite feels layered. Loose. Prone to sliding."
She leaned back slightly.
"To turn graphite into diamond is not merely to increase hardness and polish. It is closer to taking a stack of loose sheets and rebuilding it into a palace of crystal, where every part locks into a single rigorous design."
She looked at him.
"The difficulty exceeds ordinary Transfiguration of form."
"That is exactly my confusion, Professor," Regulus said at the right moment, neither rushing nor delaying.
"When I attempted it, I could sense a shared base, but the arrangement was different. Completely different."
He kept his words aligned with her framework.
"If graphite is layered and shifting, and diamond is a three dimensional structure where every point is tightly connected, then Transfiguration must achieve more than appearance."
He spoke quietly, but the idea carried weight.
"It must rewrite the internal rules. Reconstruct the structure from one stable state into another that is entirely different, yet just as stable, or more."
McGonagall listened without interrupting. Her expression turned thoughtful in a way her students rarely saw, as if Regulus had handed her a perspective she had not expected from someone so young.
At last, she allowed a faint smile.
"Exquisite insight, Mr. Black."
Her gaze sharpened again, not suspicious, but focused.
"This touches the edge of higher magic, the sort that borders on Alchemy. It even calls to mind the Philosopher's Stone."
Regulus did not react outwardly, but he absorbed the remark.
McGonagall lifted her wand. The graphite floated gently off the desk.
"Let us test the idea."
She did not speak a long incantation. She simply tapped the graphite with the tip of her wand, her eyes narrowing as her intent fixed on a single outcome.
Regulus felt the magic immediately.
It was powerful, clean, and condensed to an almost frightening purity. It wrapped the graphite like a vice made of will, not crushing it, but forcing it to obey a new set of rules.
The graphite began to change at a speed the eye could follow.
Dark grey faded. Density increased. Transparency emerged. Light caught inside the substance and fractured, as if it had learned, in moments, how to hold brilliance.
Seconds later, a clear crystal sat on the desk, unmistakably diamond hard.
McGonagall tapped it again. The edges refined, polished by an invisible force, until it became a small diamond, cut and bright, throwing candlelight into sharp sparks.
She lowered her wand.
The entire transformation had been effortless, stable, and controlled in a way Regulus could not yet replicate.
It was the difference between knowing the path and owning it.
This was what mastery looked like.