These are very beautiful Nacozari turquoise slabs acquired from Sonora, Mexico. The slabs have a beautiful turquoise blue color with just the right amount of natural darker matrix. They are all natural undyed turquoise beads which have been stabilized. Stabilization hardens and seals the turquoise making it suitable for jewelry use. The sizes of these turquoise slabs range from approximately 25mm to 55mm graduated and are approximately 6-7mm thick. Sold in a 16" strand.