In Peridot you can often see a discoid cleavage resembling a lily pad shape. These formations usually have a tiny crystal near the center, which is sometimes surrounded by a curved fracture that resembles a lily pad.
These inclusions cannot usually be seen by the naked eye and require the aid of a microscope or a jeweler’s loupe.
The inclusion is the result of a stress fracture. The inclusion in the center might be an piece of another mineral (such as chromite, spinel or biotite) or it could be a void. These voids are often referred to as negative crystals, and many of these have stress fractures.
These fractures can occur when the gemstone is heated in the ground or when heat-treated by man. Some fractures radiate in a flat, round, disc-like fashion, other fractures take on different shapes.
Lily pad inclusions are seen in peridot from all mining sources in the world.
This inclusion in never seen in synthetic material, so it is conclusive proof that the stone is in fact natural Peridot. The inclusion is also strictly seen in peridot and not in any other gemstone. Therefore, it can also be used to identify peridot from other green transparent gemstones, as well as glass.