All real US gold coins have dates but not all have a mintmarks
Your coin is either a Sovereign (22.05mm) or a Half-Sovereign (19.3mm). All Sovereigns and Half-Sovereign coins are made from 22 carat gold.
All $20.00 gold coins have .96750oz of pure gold in them.
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.
Queen Elizabeth II is on all modern British coins.
The Royal Mint did not produce an 1887 Jubilee coin. All British gold and silver coins from mid-1887 to mid-1893 inclusive had what is referred to as the Queen Victoria "Jubilee bust" on them. The "Jubilee bust" shows a much older Queen Victoria wearing a veil and a small crown.
The grading standards for gold are the same as all other coins.
Yes, gold prices can affect the value of gold coins. The value of gold coins is closely tied to the current market value of gold. As gold prices go up or down, the value of gold coins will generally follow suit.
no there not
If you refer to British coins, Queen Elizabeth II is the current head of state of England and appears on the front of all British coins.
HM Queen Elizabeth II, Queen of Canada is featured on all Canadian coins.
The standard for all gold American circulation-coins from 1837 to 1933 is 90% gold and 10% copper, so the coins are 0.900 fine which is 21.6 kt of pure gold.