What is the most common type of gemstone in the world?

The most common type of gemstone in the world is quartz. Quartz is a mineral that is found in many different types of rocks and is commonly used in jewelry making. It is a hard and durable mineral, which makes it an ideal choice for gemstones. There are many different varieties of quartz, including amethyst, citrine, and rose quartz, each with its own unique color and properties.

Other common gemstones include varieties of beryl, such as emerald and aquamarine, and varieties of corundum, such as sapphire and ruby. These gemstones are also highly valued and sought after for their beauty and durability.