It will depend on the year of issue, and the condition of the coin. Sort of like "How much is a car worth?" Depends on the year, and condition of the car. Please note that in 1986 and later 2 pound coins, they are not gold, but base metal. A pre 1986 true gold "double sovereign) has 15.98 grams of 22 K gold, and has a gold value of about $780 US dollars as of today, in addition to any collector's value.
There are 9 slightly different variants of the 1839 British Five Pound gold coin and they are all Proof FDC. The current price range is from £34,500 to £47,500 GBP. A reputable coin dealer will be able to assist with identification and give a more accurate valuation.
If you refer to a British One Pound coin issued since 1983, they are all potentially still in circulation and worth One Pound. They have a gold appearance, but are made from a nickel-brass alloy. If you refer to the 22 carat gold Sovereign issued since 1817, which has a "face value" of One Pound, any valuation would depend on the year, design and the condition of the coin.
A British 1990 Ten Pound 1/10th ounce gold coin, in absolute mint condition could fetch up to £60 GBP. A British 1990 Ten Pound 1/10th ounce gold coin (Proof FDC), in absolute mint condition could fetch up to £80 GBP. All such coins should be in their original packaging. A reputable coin dealer will be able to give a more accurate valuation.
This has no numismatic value at all
The gold plating adds nothing to the value of the coin and has no collectible value at all unless you find someone who wants it.
All British gold coins are 22 carat. There were four denominations of gold coin minted in 1902 being Five Pound, Two Pound, Sovereign and Half-Sovereign, all identical except for diameter. Please provide the diameter.
It's quite sacre, but all depends on the condition of the coin.
The gold plating adds nothing to the value of the coin. It has no collectible value at all unless you find someone who wants it. The plating actually kills the numismatic value of any coin. But the silver in the coin still has some value, today it's about $12.00.
Please post a new question with the coin's denomination. ALL 1905 U.S. gold coins had 13 stars on them. Also look on the back to see if there is a small S or D mint mark and include that in your posting.
The value of gold fluctuates, but this website has a list of all important gold coins and their details. http://www.usagold.com/gold-coins.html
Such a coin isn't a real coin and has absolutely no collector value. Rather any value comes from the precious metal content (if any) in the coin. I would take it to a jewelry store or a refiner and have them test it and see how much gold is in it (if any) and then sell it for the price of gold because such a "coin" has no collector value at all.
The British nickel-brass One Pound coin featuring the Royal Arms design on the reverse was minted for general circulation in 1983, 1993, 1998 and 2003. All issues of these coins have "DECUS ET TUTAMEN" inscribed on the edge. The only "gold" coin struck with this design was in 2008 as "Proof in gold FDC". Only 3,000 were minted.