Lower mintages do generally lead to more rarity and higher prices, but it's not so cut and dry. Probably the biggest impact on price is the number of buyers relative to the number of coins. Lower mintage euro coins like San Marino, and other smaller nations already command a premium over the larger countries. You also need to factor in what fraction of the total coins minted were collected and not circulated. Even though a large country like France will produce many million coins, it could turn out that only a small number of them were collected and kept in mint state condition. Such a scenario would lead to there being a conditional rarity for mint state coins, and the total mintage numbers wouldn't tell the whole story.
You also have to look at who is collecting the coins and why they are collecting the coins. The US has a larger number of coin collectors that only collect US coins and that's why our coins are valued so highly compared to other rarer coins from other countries. Small nations probably won't have a lot of resident collectors, so most of the value will come from foreigners who want to collect their coins. Predicting collecting trends can be a big part of predicting value.
There's a lot to consider, and even after considering it there's no way to know if you are getting it right. Generally speaking, rarer coins are worth more.
You also have to look at who is collecting the coins and why they are collecting the coins. The US has a larger number of coin collectors that only collect US coins and that's why our coins are valued so highly compared to other rarer coins from other countries. Small nations probably won't have a lot of resident collectors, so most of the value will come from foreigners who want to collect their coins. Predicting collecting trends can be a big part of predicting value.
There's a lot to consider, and even after considering it there's no way to know if you are getting it right. Generally speaking, rarer coins are worth more.



















