medium, medium-dark, or dark.
Clarity
A flawless gemstone is rare and expensive. As with diamonds, most gemstones have inclusions, or tiny mineral flaws, that can be seen under magnification or by the careful eye. Make sure that any inclusions in the stone do not penetrate deeply into the gem, as this may cause it to break or crack. Clarity grades range from VVS (very, very slightly included) to I3, in which inclusions are prominent and severely affect the gemstone's beauty.
Cut
A gemstone's cut refers to its proportions and symmetry. In making a gemstone look appealing--the stone should be symmetrical in all dimensions so that it will appear balanced, and that its facets will reflect light evenly. Color should also be taken into account when cutting for optical efficiency. If a stone's color is highly saturated, a shallow cut will allow it to pass more light, while a deeper cut may increase the vividness of a less saturated gem. There is no generally accepted grading system for gemstone cut.
Size
Though a gemstone's weight is usually given in carats, this may not give an accurate idea of its size, because different types of stone have different densities. Therefore, a one-carat sapphire or ruby will be smaller than a one-carat emerald, though they have the same weight, because sapphires and rubies (both a form of the mineral corundum) are more dense than emeralds.
Gemstones can also be measured in dimensions (diameter, length, and width). It is important to know the dimensions to ensure that the gemstone weight will be visible and well-proportioned in the setting.
