Don't use metal polish to remove the spots, Meutia. That will ruin the value of your cool British coin. Be sure to handle your coin by its edges only. No fingerprints allowed!
It sounds like you have a gold sovereign from 1914. It could be a half sovereign, because the two coins look alike, only their size is different:
HALF SOVEREIGN: 19 mm diameter, 0.118 troy ounces gold
SOVEREIGN: 22 mm diameter, 0.235 troy ounces gold
Like most of the coins in these series, the 1914 coins from the British mint are 'common date' coins, so their fundamental value comes from gold content. In other words, these coins are 'worth their weight in gold.' There are sovereigns and half sovereigns that are worth more than basic gold value. These are discussed below.
At the current gold value of about $1340 US dollars per troy ounce, your coin is worth 0.235 times $1340, or $315. The value of gold varies daily, so be sure to look it up on a web site such as Kitco.com. If you have a half sovereign, the formula is 0.118 x 1340 = $157.
Collectors often pay more than gold value alone, especially for coins that are in excellent condition. The additional value over and above the basic gold value is called 'collector premium.' For a nice, fully uncirculated specimen expect a collector premium of about $100 US dollars for a sovereign, and half that for a half sovereign. If you want to sell your gold coin to a coin dealer, expect to get offers well below the retail price. The dealer needs that margin to keep his or her business afloat.
The coin in our picture is in beautiful condition. It has plenty of creamy mint luster, which means it is uncirculated or nearly uncirculated. It comes from respected eBay seller Allgold Coins US in London and New York. CoinQuest thanks Allgold Coins US for use of their coin photo. It is a beauty!
If you have a 1917 sovereign from Great Britain (without mint mark, see below) you have a *good date* and it is worth a lot of money. Hope you've got one. The catalogs say a 1917 sovereign without mint mark is worth $6500 in well preserved condition.
Now, Meutia, here is the tantalizing part. Your coin was probably minted in Great Britain and carries no mint mark. But, if it has a C mint mark (Ottawa, Canada), it is worth a lot. Look at the side with the dragon slayer, just above the date. What do you see? You may need a magnifying glass to see it. If you see no mint mark, then the discussion above applies. If you see C, for the Canadian mint, then you have a valuable coin. A 1914C sovereign catalogs for $1500 in uncirculated condition. If you have one of these, that's great!
The picture shows what an M mint mark (Melbourne, Australia) would look like. There are other mint marks for this series of sovereigns, and some are quite valuable. Here is a listing of the good mint-marked coins. The catalog value shown is for well preserved specimens.
P = Perth, Australia
M = Melbourne, Australia
S = Sydney, Australia
C = Canada
If you have one of the coins in the lists above, you are beyond the ken of CoinQuest. Seek out a knowledgable coin collector or coin dealer. Your coin carries numismatic (coin collector) value well beyond its basic gold value.
Finally, as with all valuable collector coins, a mint marked coin might be a counterfeit. So it is best to work with reliable dealers and have your coin authenticated, graded, and encapsulated by PCGS, NGC, ICG, or ANACS. Look them up on the Internet. Do not use other services.