Tourmaline Ring, Black Raw Crystal Round 925 Sterling Silver, r2Raw Black Tourmaline Ring, 925 Sterling Silver. Raw Tourmaline Crystal with the natural striations along the Crystal Length showing very clearly with nice sharply defined edges. Bezel set in 925 Sterling Silver and open backed to allow the energies of the stone to flow more freely with yours. Tourmaline is famously the most energising of all crystals and gemstones. It increases the flow of energy along all your energy lines which both unblocks them