The name Peridot is a girl's name of Arabic origin meaning "a green gemstone". Peridot and is often added to lists like Jewel and Gemstone Baby Names and discussed in our forums with posts like "Baby a Day".
From the experts:
Peridot is the gem of the month of August, a vibrant green mineral, said to be good for helping people put the past behind them, and an interesting, undiscovered jewel name. It was regarded in ancient times as the symbol of the sun.
Peridots figure in the mythologies of several cultures, including the ancient Egyptian and Roman. They are highly valued in Hawaii, where it is believed that they are the tears of the volcano goddess Pele.
If you want a truly original gem name, you might consider this instead of Opal or Ruby.