Yes, Carnelian can go in water because it’s Mohs rating of 6.5 makes it water safe.
Anything over 5.0 is considered to be water safe.
It’s important to note that, like most gemstones, carnelian can be sensitive to sudden temperature changes, so it’s best to avoid exposing it to extreme temperatures, such as boiling water or a sauna.
Also, some carnelian may be treated with resin or wax to enhance its color and appearance, and those treatments might not be stable in water.
So, it is best to check if the carnelian is treated before exposing it to water.