Black Tourmaline is grounding and protective. This is one of the crystals that I use in my protection grids. Great to place by a door for protection.
 
If you want it to stand guard by your door, "plant" it in a pot with soil.
 
1 - 2.25" x 1" x .75" - $3.50
2 - 2" x  1" x 1" - $3.50
3 - 2.5" x 1" x .75" - $3.75
4 - 2" x 1.25" x 1" - $4.00
5 - 2.25" x 1" x .75" - $3.50
6 - 2.5" x 1.25" x 1" - $5.00