The chain is approx. 47/49 cm with/without the medallion.
Although the pentagram is the symbol of Venus, in its inverted form it is interpreted as a Satanic symbol and associated with the devil. In Medieval times, it was considered protection against evil and prevented ill-willed spirits from entering houses as long as it was painted on their door frames. The green "jewel" at the center of the pentagram gives the medallion a magical aura. By the way: our pentagram is upright.