Whilst this is all about flower essences, the same principals apply to gem essences as well, but the crystals need to be much cleansed first or you can add the negativity they store into the essence as well.
Do this under the moon and sun up to for 2 weeks, in salt water or over a copper pyramid.
Only use pure water as distilled water as any chemical in the water may weaken the properties of the crystal used.
Leave the essence over day and night for the yin and yang balance needed.
I have bowls of crystals in water all the time—in fountains and outside and sometimes I am asked to use this water as part of the essence. Occasionally some of my crystals want to be in the hatchling water or just want to be beside it, so I allow that. It’s all about learning to trust feelings. Some crystals add their energies without actually being there too.
Gem essences are often more powerful as they can also utilise off world energies. Crystals focus energies in a different way to the floral kingdom which is very much more earth energies which also interact with stars, the sun and so on. Gems come from deep within the earth and so hold ancient memories and energies. As man was evolving, so were many crystals and so we do share the resonance of some, which will strengthen our own.
Working with gem essences takes much care and trust to get it right. Your intent and connection will greatly aid the process.