Back in Crystal Generators £19.95 
Rose quartz 
Obsidian 
Quartz 
Amethyst 
The idea with these are that the are like a mini grid, the crystal points direct energy outwards, so by having these in your home they can be used for their protective/loving/Amplifying energies directing that energy out into the space in which your using it. 
So in a room which may feel like it needs an energy shift would be a good place. 
Or even over a blocked Chakra.