What exactly does "Yihe's face, ancient silver paper" mean?

Jardine Matheson refers to the British company Jardine Matheson, and Swire refers to Swire Group Limited. These two companies are British companies and have been doing business in Hong Kong for a long time.

"Jardine's face, ancient silver paper": it means Jardine's face is big (and proud); Swire has a lot of silver.

"Silver paper" should be "silver".

Jar SGX: J36, LSE:JAR is the most famous old British foreign firm in Qing Dynasty, and the largest British consortium in the Far East, engaged in trade with China. (See Baidu)

Swire foreign firm is a British-owned foreign firm with a long history, which was engaged in trade with China during the Qing Dynasty. Today, Swire's business covers four continents, mainly in Asia, Pacific coast, Australia and the United States, covering a wide range, from aviation and shipping to various manufacturing and engineering industries, beverages, real estate, refrigeration, insurance, agriculture and retail. Most of its business in Greater China uses the name of Swire. From 1860 to 186 1, John Swire's descendants turned to another completely different place of business-China under the closed Qing government, where they imported tea and silk and exported textiles to China. ..... In the Far East, the name "Taikoo" is still widely known. (See Baidu)