An unholy symbol is a silver symbol blessed to imbue it with the unholy power of Zamorak. Players can only smelt and string the symbol after completing Observatory Quest and speaking to the Spirit of Scorpius, but it is not required to bless the symbol with an Unholy book or Book of balance, or to buy it from another player and wear it. Unlocking the ability to craft unholy symbols is a requirement of the master quest cape.
If players wear an unholy symbol while in the waiting room of Saradomin in Castle Wars, they will be transformed into a rabbit. If players enter the Guthix portal wearing an unholy symbol, they will turn into sheep until the start of the next game.
When the item was first released, it was not tradeable.
Before an update it used to be made from gold instead of silver. Again, after a hidden update, the symbol's colour was changed to silver. After yet another update, they are currently made from silver, but the symbol is gold in colour with an unknown grey piece accompanying it.