The Bello Opal Stacking Ring features a 4mm White Bello Opal on a 1.5mm band. This ring is made with 1/20 14k Gold and is water friendly. Gold filled rings will last for years and years if cared for properly. Avoid contact with chemicals and store separately in a small ziplock or air tight pouch when not in use. Opal: 4mm White Bello Opal- synthetic - will not change colors or yellow over time. Material: 1/20 14k Gold Filled Gold-filled is an excellent alternative to solid gold. Since gold is heat bonded, it won’t fade or lose color. It can chip off if damaged by chemicals, so avoid those.