This set is of five 25 yuan, 1/4 oz platinum coins from the 1993 Scientific and Technical Inventions and Discoveries of Ancient China series. The complete 1993 series contains twenty-two coins: nine gold, eight silver, and five platinum. The reverse of the coins in the series show various inventions and discoveries of ancient China. On the obverse side of all the coins there is an image of a section of the Great Wall featuring a prominent guard tower on a hill. The Great Wall was built during the Qin Dynasty (221-206 BC), the dynasty that unified China, to keep out the barbarians to the north. The characters printed above the tower read: “The People’s Republic of China.” Beneath the image of the tower is the year of issue, 1993. The set of five platinum coins are all proof coins with a purity of 99.95% and a mintage of 100 each.
The reverse of the five coins show five different inventions or discoveries of ancient China:
The first represents the invention of the stirrup and shows two horses and riders in the foreground playing sport with a picture of a stirrup in the background. The stirrup was invented in China around the 3rd Century AD.
The second represents the unearthing of the Terracotta Warriors, the ghostly life-size pottery soldiers who were made to guard the soul of the First Emperor of China, Qin Shi Huangdi (259-210 BC), in the afterlife. In the background stand three terracotta figures and two burial mounds.
The third represents the mathematical definition of zero, a concept which emerged in China in the 3rd Century BC. Three mathematicians are pictured surrounding a counting board. A counting rod and an abacus are shown above them.
The fourth represents the creation of the concept of yin-yang, the Taoist symbol of balance and the complementary nature of opposites, particularly between Heaven and Earth, by the Taoist sage Laozi (circa. 5th Century BC). One scholar is pictured standing on the right, while another kneels on a mat to the left. A yin-yang symbol lays on the ground between them. Above them is a yin-yang surrounded by the eight Taoist cosmological trigrams.
The fifth represents the invention of the umbrella around the 4th Century AD. In the foreground are two craftsmen or inventors working on an umbrella, one sits at work while the other stands watching over him. In the background four women are shown standing around, each holding an umbrella.