Agate is one of the world's most-prized minerals. It is a microcrystalline variety of quartz and is typically formed in volcanic rock. Its natural hardness makes it perfect for jewelry, carvings, bookends, coasters and clocks. Our magnificent Agate coaster features a high quality and hand-polished Brazilian stone. As you will see from our Amazon shop page, coasters can be purchased with silver or gold plated edges to further enhance the beauty of the piece or you can buy pre-made sets of four or six coasters. Due to the characteristics of the natural stone, coasters vary in color and size. Coasters make great gifts for men and women and are perfect additions to everyone's home decor.