Natural stones (stones that can be used in jewelry after cutting and polishing) are well-known for their vibrant colors, but are not one of the four precious stones (diamond, emerald, ruby, sapphire).
Resin is a "solid or highly viscous substance," which are typically convertible into polymers. Such viscous substances can be plant-derived or synthetic in origin. They are often mixtures of organic compounds. It is durable and transparent, and starts as a liquid form. After casting, it becomes solid and resilient. Special resin molds with smooth surfaces are created to give it a glossy finish.