Such a coin does not exist. Threepences have never been made from copper.
Yes, the 1939 coin is worth more, but only in Mint Uncirculated condition, otherwise they are worth about the same. The 1942 "One Dot" Threepence is a minting error and represents about 8% of the 1942 Threepences minted.
Any collector value would depend on the country of origin and the condition of the coin.
All Australian Pennies minted from 1938 to 1964 inclusive feature a kangaroo on the reverse. The only Australian coins to feature wheat was the 1938 to 1964 inclusive, silver Threepence coins.
There is no documented evidence of a 1942 Threepence with a blank reverse, but any genuine minting defect or irregularity would increase the value of the coin. A British 1942 Threepence (was only minted for Colonial use), uncirculated and in absolute mint condition could fetch up to £40 GBP. If it has been circulated but still in good condition, it might fetch up to £5 to £15 GBP. A British 1942 Threepence (dodecagonal - nickel brass), uncirculated and in absolute mint condition could fetch up to £7 GBP. If it has been circulated but still in good condition, it might fetch up to £2 GBP. A reputable coin dealer will be able to give a more accurate valuation.
The rarest general circulation Australian Threepence, as distinct from the most valuable, would be the 1942 Threepence minted in Melbourne of which there were 520,000 minted. The other Threepences minted in 1942 were minted in the San Francisco (mintmark = S) and Denver (mintmark = D) mints in the USA. Threepences from this period that were struck in Melbourne have no mint mark. All others will have a mint mark on the reverse below the fourth digit of the year indicating the city where minting occured.
The small 50% silver Threepences (16mm) were still being minted for the Colonies from 1942 to 1945 inclusive. The changeover to the 12 sided nickel-brass Threepence (21mm) commenced gradually from 1937.
Such a coin does not exist. All Australian Threepences from 1910 to 1944 inclusive were made from sterling silver.
It depends on the type of threepence. A nickel-brass (multiple sided) threepence is rather common and would sell for 50p to a pound or so if circulated. A silver threepence on the other hand is 50% silver (and much smaller) and worth about a pound or two mostly for the silver if circulated.
"Victorian times" covers a period from 1837 to 1901 inclusive. A Threepence as the name suggests, was worth three pence. Threepence GBP in 1850 had the purchasing power of about £0.90 GBP today. NOTE - This historical conversion is the result of many calculations and considerations by a purpose designed program. The resulting answer should only be regarded as an approximation based on current exchange rates.
There are 2 Halfpennies to the Penny. There are 3 Pennies to the Threepence. There are 6 Halfpennies to the Threepence.
There were no Australian Threepences minted prior to 1910.
A 1942 wheat penny is worth 2 cents for the copper.