Chalcedony to as prase. However, the term prase is also used to describe green quartz, and to a certain extent is a color-descriptor, rather than a rigorously defined mineral variety.) Blue-colored chalcedony is sometimes referred to as "blue chrysoprase" if the color is sufficiently rich, though it derives its color from the presence of copper and is largely unrelated to nickel-bearing chrysoprase. Heliotrope is a green variety of chalcedony, containing red inclusions of iron oxide that resemble drops of blood, giving heliotrope its alternative name of bloodstone. In a similar variety, the spots are yellow instead, known as plasma. Moss agate
Diamond enhancement good as their non-enhanced counterparts. The clarity, or "purity", of a diamond refers to internal inclusions of the diamond, and is one of the 4-C's in determining a diamonds' value. Common "inclusions" that appear inside diamonds are black carbon spots and small cracks, commonly referred to as fractures or "feathers", due to their feathery whitish appearance when viewed from above or through the side. Diamonds may also have other inclusions such as air bubbles and mineral deposits such as iron or garnet. The size, color, and position of the inclusions are factors in determining the value of a diamond, especially