Very fun game! I made it to Level 17 with very little difficulty.
I would suggest spawning the gems within hidden tiles to increase difficulty. Some levels, I was given 80% of the gems needed to proceed to the next level without even touching a tile.
The only other suggestion I would make is to include a flagging feature within the game. It can be more difficult having to remember which tiles are bombs.
I loved the safeguards in place so that I could not accidentally hit a tile I did not intent to hit, very good idea needing to hit the tile 3 times to break. The music was perfect for the introspective headspace that a minesweeper roguelike requires. Bravo!