gems are basically just passive boosters. they are always active and give buffs to whoever wields them. the downside of this, however, is that they can shatter. when a gem uses its passive ability (for example, boosting how much money your workers gain) it has a very small chance to shatter. while this chance is small, it adds up over time.
using gems that can shatter based on command usage is risky and should only be done if you have a crystal heart (more info below), want to get a crystal heart, or want to actually receive the effects of the gem, even if it shatters.
having more than 1 of a single colour gem does nothing. for example, having 2 green gems doesn’t stack the effect, although more than one of some are needed to craft higher tier gems.
the way you obtain a gem varies on which gem you want to obtain. each one has multiple different ways of obtaining, all of which are broken down in more detail below.
scratch cards can also drop gems. some gems have a slight chance to spawn depending on which scratch card you use.
double cookies from baking only take the highest chance from all gems
the effects listed of each gem are averaged. this means that at any given time their effects could be higher or lower than what’s listed.
ranged values (ex: 1-17%) have an equal chance for all options
+20% max storage for all workers
crafting: 10 gem shards
tower: 1.5% chance to spawn per row (max 1 per game), 0.5% chance to drop when clicked
mines: 20% chance to spawn,
1% chance to obtain when buying an item from the store (NOT the shop)
cannot shatter