“Song [dynasty] workshops excelled in firing techniques, methods of forming, carving, design, and glaze making. Glazes were quiet and subdued in appearance, yet, if you held a teacup in your hand or gave a bowl more than a glance, you would notice subtle variations. The longer you looked, the more you saw. . . . There were shimmering celadons, silky whites, iron-rich dark tenmokus (sometimes with the shadow of a single, saturated golden leaf fired into the interior of a bowl), and the legendary opalescent chuns (jun) with tints of blue and purple and red. In chuns, bubbles are suspended inside the fired glaze, thus bending and refracting the light, making the eye see blue, though there are indeed no blue colorants in the glaze. Reds, and purple flashes, came from the copper.”

—Suzanne Stauback, from Clay: The History and Evolution of Humankind’s Relationship with Earth’s Most Primal Element, 2005.