Any Halfpenny coins circulating in Gibraltar in 1917 would have been British Halfpenny coins.
There were was no Australian 1956 Halfpenny minted.
The last Australian Halfpenny was minted in 1964.
The last Australian Halfpenny was minted in 1964.
The last Australian Halfpenny was issued in 1964.
There was no 1948 New Zealand Halfpenny minted.
An Australian 1917 bronze Halfpenny (George V), uncirculated and in absolute mint condition could fetch up to $480 AUD. If it has been circulated but still in good condition, it might fetch anything from $0.75 to $70 AUD. There were 5.760 million minted. A reputable coin dealer will be able to give a more accurate valuation.
The Halfpenny has never been minted in silver. If you have a "silver" Halfpenny, it is possibly because somebody has silver plated it. Modified coins have no collector value. For future reference, please provide a year.
The Royal Australian Mint produced no Australian Halfpenny coins from 1956 to 1958 inclusive.
The Royal Australian Mint produced no Australian Halfpenny coins from 1956 to 1958 inclusive.
New Zealand has never issued a silver Halfpenny. Somebody has possibly silver plated it. Modified coins have no collector value.
Such a coin does not exist. In the event that somebody did produce a gold Halfpenny, it would be worth whatever the current bullion value of gold is.
Modified coins have no collector value. Any value would be associated with the ring.