In the 1860s, Hong Kong used a 1-mil coin; a mil was worth a tenth of a cent. Mil coins, of which there are three known types, were made of bronze and, with their center holes, did not feature an image of British monarch Queen Victoria; they show a square approximation of a royal crown instead.
All mil coins feature an English side and a Chinese side. The English side features the name of the colony, the date, and the denomination written out as ONE MIL. (Despite this, some modern sources spell the unit of currency as “mill”.) The Chinese side has the name Hong Kong as 香港, written vertically, plus the value, written in one of two styles. The differences between all three different mil coins are:
Hong Kong rare banknotes and collectible paper money
KM #1: 1863, 1864, 1865
This one mil coin, the first, uses a hyphen in the English name: HONG-KONG. The Chinese value is written as 一文 (but on the coin itself, right to left, unlike here). This is pronounced, approximately, yi wen.
KM #2: 1865
This coin is just like the previous one, except the hyphen has been removed from the English name: HONG KONG.
KM #3: 1866
The final version of the one mil Hong Kong coin puts the hyphen back in the name (HONG-KONG), and changes the denomination in Chinese to 一千, pronounced yi chi-en and meaning “one thousand”, its decimal value in dollars.
After four short years of use, one mil coins were discontinued due to unpopularity with people in Hong Kong. Silver coins with larger denominations proved much more popular. Although there are generally not huge numbers of mil coins from Hong Kong available for sale, there are often a few, and none of the versions is particularly rarer than the others (proofs excepted). Interested collectors can look through the current listings and look for nice examples, whether you’re looking for a single mil coin or perhaps a complete four-year set.