Rarity or the Location

Color

Carat
Carat refers to the weight of the gemstone; one carat is 1/5th of a gram, it looks easy to understand that value increases with the increase in carat weight, but there is a catch. With the increase in carat weight, it becomes difficult to maintain other 3Cs in the gemstone. If a gemstone in its higher carat weight maintains uniform color, flawless clarity, and the best cut, it becomes more expensive. Otherwise, the value of a gemstone does not increase relatively after a certain carat weight. Another reason higher carat gemstones are not so expensive is that larger chunks are not suitable for jewelry purposes.
Clarity
The clarity of a gemstone refers to interruptions (or lack of them) you face when you try to see through it. It is also a significant factor in measuring the worth of a gemstone. Two factors can affect clarity: one is the inclusions that a gemstone has, and the other is imperfections or scratches on the surface. Inclusions are not always responsible for downgrading the value of a gemstone. A star sapphire derives its value from needle-like inclusions.
Cut
A high-quality cut not only measures the gemstone’s worth but is an art that brings you the best out of the raw gemstone. While cutting a gemstone crystal, maintaining clarity, and keeping the wastage at a minimum level is walking on the edge of the knife because a slight imperfection can waste all the effort this is why the cut of a gemstone is a countable factor in the overall value. A cut of gemstone in which light cannot hide, and we get the maximum brilliance is the most valuable one.