Hammered coins were made in England from the reign of William 1st in 1066, right up to 1662. In the earlier periods, most of the coins were struck in gold and silver. The coins are usually a little buckled, and the sides of the coin are seldom perfectly round due to the hammering process. Hammered coins were made by taking a circular metal blank, called the flan, and placing it between two dies. One die was engraved with the obverse (heads side) and the other with the reverse (tails side) of the coin to be produced. The obverse side would then be struck with a hammer and the engraved details were ingrained on both sides of the flan. To identify a hammered British silver coin, a collector would need to look for specific mint marks and other engravings.
Look at the coin and make sure that it is not perfectly round and smooth like a modern-day coin. It should be slightly buckled, and the edges should be a little rough.
Using the magnifying glass, check that the obverse side of the coin has the bust of a monarch with his or her name and title. The name and title of the monarch is always abbreviated and always in Latin.
Check the name and title of the monarch against a credible book, such as "The Kings and Queens of England" by Ian Crofton, to determine the time period in history when that monarch was on the throne.
Look at the reverse side of the coin and make sure it has a design, the name of the moneyer, the date and town (or mint) where the coin was made.
Although all the legends (the name given to the coin engraving) are in Latin and are usually in abbreviated form, there is an exception, this being the Commonwealth issues 1649 to 1660. A mint mark was used to characterise a coin. From the mint mark it is possible to tell who made it, the date it was made, and often the town where the coin was minted. This was so that badly made coins could be traced back to their maker.
Identifying coins takes a fair amount knowledge and skill, as this is a specialist area. It would be good to start collecting by first buying them through a reputable dealer, and getting to know the reigning monarchs and their mint marks before trying to buy coins from less reputable sources.