Grow a Blue Crystal by Thames & Kosmos
Grow sparkling, blue crystals overnight from a safe solution of potassium aluminum sulfate. Single out the largest crystal shard, redissolve the remaining crystals, and repeat the crystal formation process to grow a larger, more striking crystal. These kits include all the materials and tools you need to grow a single crystal, as well as a small hexagonal storage box in which to keep your crystal safe. Also available in pink, green, and yellow.