Conuld looks a bit taken aback to be put on the spot in front of everyone. "Ah, well," he begins. He tugs at his earlobe nervously. "All right. Allow me to make a small demonstration." He moves his hands in odd patterns and speaks a few words. "If you would excuse me for a moment?" He picks up a bowl, which is suddenly mysteriously clean, and heads out into the courtyard.
Shortly, he returns, with a small amount of sand in the bowl. "This is something you have no shortage of, I believe," he says. "Observe." He pours the sand onto the table, cups his hands over it, and when he lifts them, a somewhat shapeless ball of glass is revealed. Somehow he manages to mould this into a flat sheet with the heel of his hand. "I am sure you already know which stones are suitable for mixing with sand such that in their melting they combine to make fine glass. Would it were as easy as this to make glass that will endure. But this is magic which cannot last more than an hour." In another moment, the glass sheet is flat, polished and shiny.
Conuld then takes a small stick of wood from his pouch. He glances at Cludge and gives the smallest of winks as he holds up his forefinger, from which shoots suddenly a jet of flame. He holds it to the stick and watches it burn. When the end is thoroughly charred, he snaps it off, and with a flourish of his hand, he is holding a diamond.
"I am afraid this too is a form of deception. The diamond is real for now - well, moderately real. It is not quite as hard as it should be, I think. It remembers that it was but a moment ago a piece of burned wood, and it is anxious to return to that form. Anyway, I believe I can incise letters in this glass with a diamond more swiftly and more finely than a stonemason can cut letters in stone, though as I am no craftsman, I am afraid I will do it with less beauty. I shall write a short message now."
He does so, taking a little time over the task. "That is enough to see," he announces. "It is adequately legible. Perhaps if I -" He runs his fingers along one edge of the glass sheet and some ill-defined spongy material forms there. Then casting again, he touches the strip, and it glows brightly. He turns the sheet, angling it so the light shines through the fine scratchings in the surface. "Yes, perhaps side-lighting would be effective." He passes the sheet over to Gram. "Well, I hope you see what is my thought. Though a single sheet is fragile, great stacks of glass, each inscribed, could last almost forever. Er, it would be best if the glass were to be put back outside again shortly, before it crumbles into sand and makes a mess."
OOC: the many and varied uses of prestidigitation, and light