If the coin has an "S" mintmark it's Proof, if not, it's the uncirculated version. Current average retail value for a Proof coin is $40.00 Uncirculated is about $29.00.
Uncirculated and Proof versions of this coin were struck, but value is the same for both at $6.00
Even with a Proof coin grade drives value. So from $3,000.00 to $20,000.00.
This is a proof coin not made for circulation, if it was found in pocket change the value is 50 cents.
The 5 coin proof set has a value of $6, the 10 coin set has a value of $15 and the 10 coin silver set has a value of $48.
Average retail value for the Proof coin is about $40.00.
In mint state condition it has a value of $1500 to $4200 depending upon the condition of the coin. In proof condition the value varies from $1500 to $2700.
If the coin is .999 silver value is about $27.00.
An Australian 1986 5 cent coin (Proof), uncirculated and in absolute mint condition could fetch up to $5 AUD. The Australian 1986 5 cent was only ever issued in a "Mint Set". A reputable coin dealer will be able to give a more accurate valuation.
These coins are no longer in circulation since Irelands changeover to the Euro in 2002. Unless they are part of a Proof or Uncirculated mint set or are individual Proof or Uncirculated coins and in absolute mint condition, they have little or no value.
If you mean a 1986 Statue of Liberty Centennial half dollar? This coin was struck in copper-nickel not silver. The Denver Mint coin is uncirculated and the San Francisco Mint coin is proof. Both have the same retail value of $6.00. A 1986 Kennedy half dollar is just 50 cents.
With difficulty. The British Halfcrown coin has been issued since 1526. Are your coins circulated (what condition are they in), mint uncirculated, or Proof? Do you have a full range issued for a particular king or queen? Do you have an example of every coin issued between certain years? Does your collection include varieties? I suggest that you take your collection to a reputable coin dealer in your area and ask for a valuation.