Complex sentence: Jewellery may be made from a wide range of materials, but gemstones and similar materials such as amber and coral, precious metals, beads, and shells have been widely used, and enamel has often been important.
Split into simpler sentences: Jewellery may be made from a wide range of materials. Gemstones and similar materials such as amber and coral, precious metals, beads, and shells have been widely used, and enamel has often been important.