Mix of czech glass beads and 14 k gold filled. Elastic ring.  Note: Gold-filled shouldn't but can tarnish due to the 95% brass core inside and 5% gold sheet over brass by weight. A good gold polishing cloth or jewelry cleaner will help to remove tarnishing. Unlike gold plated product with has nano thickness of gold on the surface gold-filled do not lose the layer of gold easily because it has 5% gold sheet over brass. However swimming in pools, sunscreen, hair products, nail polish, bleach, perfume chemicals, nail and hair salons with high-level sulfides in the air, hot springs can permanently cause damage to gold filled.