I'm designing a board game about gem collecting. To collect gems players must invest on different gems in their turns (i.e. resource collecting is done using investment). Investment part in my design is as simple as follows:
There are 6 mines that can produce different gems, numbered 1 through 6. Each player chooses 3 gem mines then toss a d6 die. If the die number is equal to one of the chosen gem mines, then the player collects a gem.
This mechanic doesn't work too well for me, so I am looking for suggestions to improve it.
If you have a suggestion and you know that another game exists that uses a similar mechanic, please include that in your answer.