Throughout the day our crystals absorb our energy as well as the energy of others around us. Carrying around a load of toxic energy is not a good way to gain the most from your crystals. This is why cleansing your crystals is important. There are several ways to do this and if you're like me with limited time you will have to pick a method that works best for you. Feel free to switch up your routine if you'd like. There are more methods than the ones i mention below, but i picked out the most common methods.
Sun & Moon
Place your crystals in a windowsill or somewhere where the rays from the sun or moon will hit. Leave for 24 hours to allow a full cleanse. Even on cloudy days when the sun or moon is not visible, this method still works. Note: Some crystals such as Amethyst and Rose Quartz may fade in the sun using this method over time so you may want use an alternative method for these.
Earth
Place your crystals, jewelry, or any gemstone in a cloth and place outside in the soil. Keep there for 24 hours to let them become fully energized. For an even more amazing experience, do this same process during the full moon. Remember to not forget where you bury them!
Smudging
Using white sage or palo santo, burn it until you get a good amount of smoke. Have your crystals ready and hold them in the smoke for about 1-4 minutes as they are being cleansed. Mentally clear your mind from any disturbances and focus on removing all negative energy from the crystal. This is one of my favorite methods because not only are you cleansing your crystals, but your home as well.