What a nice game!
I am very impressed how much stuff you managed to get done in such an amount of time.
The only few suggestions for improvement that I have are these:
1) Indicate it to the player in some clearer way when they get a new employee in the shop
First time I played I suddenly realized I got 6 of those when I was still playing with only 3.
2) Maybe change the cell size from 16x16 to 14x14, that would make things snap better.
3) Do something with the topazes, in the menu it's yellow on top of yellow, literally invisible.