While Australia remains a Constitutional Monarchy, the reigning king or queen will be on all of Australia's coins as the nominal "Head of State" (Queen of Australia).
Currently, and since 1953, Queen Elizabeth II has featured on the obverse of all Australian Coins.
$40,000 Australian Dollars $40,000 Australian Dollars
If you refer to the "diamonds" on the obverse side of Australian Pennies (and all other Australian coins from 1953 to 1964), they are merely a spacer. The function was previously performed by a semicolon and/or a full stop on pre-1953 coins.
The kangaroo and the emu are on the Australian coat of arms. They hold the shield which features on e coat of arms.
I think you mean "Obverse", which refers to the front of the coin (usually, but not always, the side with the portrait or coat of arms), as versus the "Reverse", which refers to the back of the coin.
The current Australian Five Dollar note features Queen Elizabeth II on the front and a view of the new and old Parliament Houses on the reverse.
If you're referring only to Australian coins struck only in 1966: 1. The 1966 Australian 50¢ has 0.3415 ozt pure silver in it; 2. The 1966 Australian "Wavy Baseline" 20¢ is worth between approximately $200 and $4,000 at the moment. This is a rare type of 1966 20¢ - it is quite rare and has a different shape to the base of the 2 on the reverse (tails side).
The Australian Five Dollar note featuring Queen Elizabeth II on the obverse, has a branch of eucalyptus (gum) leaves and flowers on the left hand side. The species is Scribbly Gum (Eucalyptus haemastoma). The transparent holographic device in the lower right hand corner has a stylised representation of a gum flower.
The obverse (heads) side features a portrait of Queen Elizabeth II. The same portrait was used on all Canadian coins 1965-1991. The reverse (tails) side features a lynx.
Actually those initials appear on many Canadian denominations and older Australian Coins as well. KG is the initials of the designer (George Kruger Gray) of the reverse (tails) side of the coin.
Any 1942, 1943 or 1944 Australian Threepence, will have the "S" (San Francisco) or "D" (Denver) mintmark on the reverse of the coin, on the right hand side, just below the fourth digit of the year. Any coins minted in Melbourne will have no mintmark.
IRB is the initials of the designer (Ian Rank-Broadley) of the Fourth Portrait of Queen Elizabeth II used on many coins of the Commonwealth countries, including Australia.
A Platinum Koala is a precious metal bullion coin minted by the Perth Mint in Australia. It is part of the Australian Koala coin series, featuring the iconic koala design on the reverse side. These coins are made of .9995 fine platinum and are sought after by investors and collectors for their rarity and purity.