How long can a clear quartz crystal, if unused and left alone, hold its charge for?

If this is related to its size/shape/how clear it is (or being male/female) please let me know your experiences in that regard. I am thinking of buying a few clear quartz, charging them up when its sunny, and leaving them till I need them, as in England its not often sunny :D

It is possible on the third eye they help give you the energy to recall dreams with more clarity. - I am only testing this at present, but I have noticed it to be incredibly soothing, some days, a bit like rose quartz/amethyst/sodalite can be depending on the day.

Any other tips for clear quartz? Do you have any other methods of charging you find reliable, I use selenite at the center of all my crystals to clear them. 


The magnification of other crystals has been suggested, but I am not one to live in fear, so I just get on with using a lot of different types to see the effects, all with a healthy dose of Amethyst a part of a geode and two other crystals at various points where I sleep acting as a good balancing point for the age we have placed ourselves in.

Gratitude manifested and sent for reading.