The grading system used on gemstones is just like that of diamonds, but also considers the following: transparent, with transmits light without serious diffusion; translucent, which allows light to pass through, but only diffusely (semi-transparent); and opaque, which does not allow light to pass through. The grading system also takes into account the type of stone that is being graded. Type I gemstones include stones that naturally have few inclusions. Among these are aquamarine and topaz. Type II gemstones include stones that generally have a few natural inclusions. The most commonly used gemstone of this type is the garnet. Type III gemstones are the stones the generally carry a lot of inclusions based on the process required to create them. Among these are emeralds and tourmaline.