A tropical dial refers to a watch dial that has undergone a change in color or appearance due to prolonged exposure to environmental factors such as sunlight and humidity. This phenomenon is typically observed in vintage watches, where the original dial color fades or transforms into a unique patina, often resulting in a brownish hue. The change is usually unintentional, occurring because earlier watch dials lacked adequate UV protection. Despite being a result of aging and environmental exposure, tropical dials are highly valued by collectors and enthusiasts for their distinctive and rare appearance. The patina developed over time gives each tropical dial a unique character, making these watches sought after in the vintage watch market.