Chinese coins have been found in Yapahuwa and date back to the period when Lanka paid tribute and was visited six times by Admiral Zheng between 1405 and 1433. 600 years later, China has minted coins for the Central Bank (CB) to celebrate its 70th anniversary. A commemorative 20-rupee Aluminium Bronze collector coin was sold to the public on January 1 for Rs.1300.

Made of Aluminium Bronze, unlike the Silver coins minted for the 40th, 50th, and 60th CB anniversaries, the coin is seven lobed sided, and a specified diameter of 28 mm and 2 mm thickness. The weight not specified was measured at 8.7 grams, approximately to the weight and size of the old Rs. 2 coin except for the shape.

The obverse has image of the CB building and the reverse is similar in design to the new 2017 coins

This coin was planned to be issued on August 20, 2020 and was delayed by the COVID-19 pandemic as the shipment of circulation coins had not yet arrived.

An advance limited lot of 3000 Brilliant Uncirculated coins in presentation boxes, with certificates of authenticity, were air-freighted. The first coin was officially presented to President Gotabaya Rajapaksa, by CB Governor Prof. W D Lakshman on December 31, 2020.

To read the complete article, see:
Chinese mint new Rs.20 coin for Central Bank(http://www.sundaytimes.lk/210110/business-times/chinese-mint-new-rs-20-coin-for-central-bank-427252.html)

To read about the coin on Kavan;s website, see:
2020 - Sri Lanka - 20 RupeesCentral Bank of Sri Lanka70th Anniversary(http://coins.lakdiva.org/commemorative/2020_cbsl70_20r.html)

Kavan adds:

To watch the lecture, see:
Lankan Commemorative Coins(https://www.youtube.com/watch?v=T1SWXg9A5Hc#t=3m36s)