Inclusion (mineral) - Gemology

Gemology

Inclusions are one of the most important factors when it comes to gem valuation. In many gemstones, such as diamonds, inclusions affect the clarity of the stone, diminishing the stone's value. In some stones, however, such as star sapphires, the inclusion actually increases the value of the stone.

Many colored gemstones, such as amethyst, emerald, and sapphire, are expected to have inclusions, and the inclusions do not greatly affect the stone's value. Colored gemstones are categorized into three types as follows:

• Type I colored stones include stones with very little or no inclusions. They include aquamarine, topaz and zircon.
• Type II colored stones include stones that often have a few inclusions. They include sapphire, ruby, garnet and spinel.
• Type III colored stones include stones that almost always have inclusions. Stones in this category include emerald and tourmaline.

• Clear gemstone with metallic inclusion.

• Peridot with milky inclusion.

• Natural Ruby with inclusions.