Agate/ˈæɡət/ Definition 1 of 2Pro Tip 1/3Visual Imagery When you hear 'agate' think of its distinctive bands; they're key to its beauty. Each agate has unique, wavy lines. Pro Tip 2/3Not Always Precious Agates are semi-precious; valuable, but they're not as costly as diamonds or rubies. Her agate earrings were beautiful yet affordable. Pro Tip 3/3Common Jewelry Agates are often found in everyday jewelry due to their variety and durability. I bought an agate ring at the local market.