This is a quality example of the powerful healing crystal, Moldavite, found in the Czech Republic, selected for its larger size and shape.
It was formed by the impact of a giant meteorite approximately 15 million years ago in modern day Bavaria, Germany. Glassy minerals of this type, formed by meteorite impact are known as Tektites.
Moldavite has been used from the Stone Age onwards as an amulet stone and as a good luck stone. It has extensive crystal healing properties.