Origins of Gemstones

by Douglas Floyd

Treasured by all races and religions, gemstones have captured the imagination of humans for thousands of years. Gemstones were thought to have powers of protection, healing, wisdom, invisibility, and even life. But where do gemstones come from?

Most gemstones are actually mineral crystals (except for non-mineral gems like pearls, coral, and amber). Mineral crystals form through a naturally occurring combination of chemicals, heat and/or pressure. These chemicals affect shapes and color of the crystals. Most mineral crystals are tiny, but a few can be cut into gemstones of rare beauty.

Gemstones are the crowning glory of the mineral world. While we don't consciously think about them, minerals play a role in our everyday life. They form the rocks of the earth's crust, and they fill our homes, our highways, and even our cars. Learn a little more about minerals; research the U.S. Geological Survey for an interesting fact file.

These mineral crystals formed during one of three rock-making processes and therefore fall into one of three categories: igneous rocks, sedimentary rocks, and metamorphic rocks.

Igneous Rocks

Deep within the earth's inferno is a stew of molten rock and gases called magma. As magma wells up within the earth, intense pressure builds, forcing the liquid rock toward the surface sometimes breaking through as lava. It slowly cools, forming igneous rocks, and within these rocks and gas-bubble spaces, interlocking crystals grow. The minerals present, the cooling time, and the environment all play a role in the way these crystals form. Examples of gemstones found in igneous rock include diamond, topaz, kunzite, and spinel.

Sedimentary Rocks

Rock fragments near the earth's surface are often washed into riverbeds and seabeds. Over time, layers of rock fragments, mud, and other organic and non-organic elements are compacted together in hard rock. Sometimes sea creatures, bugs, or other organic elements will get trapped within the rock formations. Examples of sedimentary rocks include limestone, shale, and sandstone. In addition, most gemstones are found in sedimentary deposits. Discovered in riverbeds, these alluvial deposits includegems such as sapphire and ruby.

Metamorphic Rocks

Lastly, intense pressure and high temperatures can actually recrystallize, transforming the composition of the rock. This can happen deep within the earth's crust, and it can also happen through direct contact with hot magma. Emerald sometimes also forms in hydrothermals associated with magma. Other examples of metamorphic gemstones include sapphire, jadeite, and peridot.

In each of the above cases, crystals grow as atoms to form a complex yet ordered structure. The structure and the mineral's chemical composition combined form the crystal's properties, such as shape, hardness, cleavage, refractive index, and more.

More Gemstone Origin Information

You can read more about gemstone formation and specific gemstone characteristics by consulting the wide selection of gemstone books from Jewelry Television®.

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