Data provider SWIFT's RMB tracker showed that in May, 1.47 percent of global payments were in yuan, a tiny amount compared to the global total but up from 1.43 percent in April. This indicated progress in the second and third steps.

Some countries in Southeast Asia, Latin America and Africa have or are ready to take yuan as an official reserve currency. It indicated the fourth and the fifth steps are burgeoning.

Yuan-denominated green bond debuts in London

Bank of China gets yuan mandate in Frankfurt

Investors are also optimistic about renminbi globalization. Bank of China's global customer survey shows that over half of the respondents expect yuan cross-border transactions to rise by 20 to 30 percent in five years. And 61 percent of overseas customers say they plan to use or increase use of yuan as a settlement currency.

Li Daokui, head of the Center for China in the World Economy under Tsinghua University, said renminbi internationalization is a long-term process and should be made gradually based on China's financial reforms, including freeing interests and reforms on foreign exchange rates.

Dai Xianglong, former central bank governor of China, forecast that it will take about 10 to 15 years to achieve a high standard of renminbi internationalization.

Among the latest moves toward renminbi internationalization is the naming of two clearing banks to handle yuan business overseas.

The central bank announced last Wednesday that it has authorized China Construction Bank to be the clearing bank for yuan business in London, and the next day named the Bank of China as clearing bank for yuan business in Frankfurt.