Of course you can charge them with your other gemstones during the full moon. In fact, once they're done charging, hold them in your hands and focus on the spell you originally cast to add a little oomph.
|Enchantments of the Faerie Realm|
by Ted Andrews
|A Witch's Guide to Faery Folk|
by Edain McCoy
|One of the more than 20 spell kits available at 13 Magickal Moons|