how do experts know what some of the ancient coins are what.. like the widows mite for example...no where in the bible does it describe what the coin looks like (i dont think)... and it doesnt say "mite" on the coin so how o they know... also....cant some of the more ancient (and even modern) coins have conterfeits easily made by people who know how to make jewelry and things like that.. just a thought.....
Counterfeit coins have been made as long as coins have been made. Check out this eBay auction for an 19th Century electrotype of an ancient Roman coin.
The 'widow mite' may well not have been the coin actually used in the famous Biblical passage, according to what I've read about the matter. But legend has been built around it, since the use of the coin is more or less contemporaneous with the event. The coin itself does possess Hebrew writing on the reverse that can be used to fix the time period through the mention of the Judean king Alexander Jannaeus (103-76 BC).
Some ancient coins do have dates on them. Regnal years of one sort or another often help. And for Roman coins, tribunal and consular years are often noted. Other times, chronology is careful established through archaeological methods. As far as counterfeiting ancient coins - it does happen. Many of these, however, are easily noticeable to the trained eye. Some do re-engrave dies, but mostly, the style of these coins are significantly off. Very few, however, do slip through. Thankfully, most of these are of rather rare coins that the average collector doesn't encounter. Coins were also counterfeited in ancient times, though not for collector reasons.
Sometimes they don't know. Have a look at some electrum fractionals, and see how many of them are attributed.
You just have to remember that not to many people here were around at the time your discussing so they really don't know. In fact not to many people anywhere were here back them so almost everything of the past is a lot of guessing, pieces of a puzzle, possibles, etc. Basically you have to assume that someone is just a good guesser. By the way did you ever wonder why there are no coins with a BC after the date?