The coins forged in Hong Kong featured the Queen's face following her coronation in February 1957.

Although the Hong Kong Monetary Authority introduced the design of the bauhinia flower in 1993 before the colony was handed over to Beijing, coins featuring the Queen's face remain the city's legal currency to this date.

As time changes, the coins, instead of our everyday money, become valuables targeted by collectors.

After the Queen died on Thursday, a seller priced a 1960 HK$1 coin at HK$250 on the online trading platform Carousell.

Another is selling a 1963 HK$0.5 coin at HK$50.

A bag of 890 HK$1 coins between 1978 and 1992 is also available at HK$1,200.

A fourth seller is selling a set of 23 coins worth HK$32.8 in total, at HK$180, indicating a four-fold jump in value.

The industry reminded us that the value of coins with the Queen's face have been increasing after the handover in 1997, but mostly new coins in special years that are never released to the public.

For example, a 1964 HK$0.5 coin is worth over HK$10,000.

The industry added the appearance of the coins also matters. Their value will become less if the color is already fading or if there are damages.