Brass is an alloy of copper and zinc. The proportions of zinc and copper can be varied to create a range of brasses with varying properties. For jewelry, the most commonly used percentages of copper and zinc is 67% and 33%. This mixture helps the brass become stronger and more durable than copper alone, which allows for superb electroplating quality, and thus, it is the perfect combination for fashion jewelry.
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.