Abalone shell gem is the most beautiful and valuable rock. They are bright in color, crystal in texture, brilliant in luster, hard and durable, and rare. They are natural mineral crystals that can be used to make jewelry, such as diamonds, crystals, emeralds, rubies, sapphires and gold emeralds (rocks, cat's eyes). There are also a few natural mineral aggregates, such as agate and opal. There are also some organic materials, such as amber, pearls, corals, coal powder and ivory, which are also included in the gem.