1866 Full gold sovereign
Victoria Young Head Shield 
Minted at the Royal Mint Sydney Australia

With the exception of the 1870 issue, all Sydney branch mint sovereigns were alloyed with 8.33% silver, hence they have a brighter yellow appearance when compared to other sovereigns. 

Most 'Australia' type sovereigns seen are generally in quite worn condition. High grade examples are seldom found and are very collectible.