Hong Hanh (According to KanJian)

The floors of the three main halls in Beijing's Forbidden City, the halls of Supreme Harmony, Middle Harmony, and Preserving Harmony, are paved with unique and precious bricks. These "gold bricks," as they were sometimes called, were exceptionally durable and resonant, capable of producing a distinct metallic ring when struck. The meticulous craftsmanship and lengthy production process justified their high cost, comparable to the value of one tael of gold.

The manufacturing process involved 29 intricate steps spanning two years. The clay, sourced from Suzhou, was refined and mixed with special ingredients before being molded into the distinctive large, square shape of the bricks. The firing process required precise temperature control to achieve the desired density and resonance. After cooling, the bricks were carefully inspected for imperfections. Only flawless examples were deemed suitable for use in the imperial palaces.