Black obsidian is a glass-like rock that forms from volcanic lava cooling quickly. In metaphysical circles, it has the aura of absolute mystery. Its energy draws you in softly, but very deeply, which makes the presence of black obsidian powerful in many ways. It is commonly used for protection, healing, truth-telling, and feng shui. ➳ These HelloPosh obsidian coasters are created from high quality obsidian slices, cut into organic geometric shapes, and polished to a smooth shine. Edges are plated with GOLD or SILVER metal. Absolutely lovely to add a touch of posh to your home. ➳ You will receive a SIMILAR set of 4 coasters as shown in the photos. Jet black agate color with shiny metal rims. The bottoms have clear rubber feet to keep from sliding around or scratching surfaces. So unique and beautiful! ➳ Size: Large coasters measure ~5" across and 1⁄4" thick. Generous size for mugs or drinking glasses!