Peridot is the gemstone that stands out among the rest not only for its fiercely bright green color but also for the many mysteries that surround it. One of the questions that I am asked most frequently about Peridot is, how is it pronounced? Here are a few things I discovered about the August Birthstone. What is Peridot? Peridot is a yellowish-green transparent variety of a mineral called Olivine, which belongs to the forsterite-fayalite mineral series. It is typically foun