A bright red resin from multiple sources including cinnabar, certain rattan palms in Indonesia (where it’s known as djerang), and the plants commonly known as rushfoil or croton. It may be difficult to tell which resin you are actually obtaining when you purchase it.
The resin has had many practical uses, including as in medicines and as a varnish. For magic it is used in spells for love and for protection. It is also used to make a red ink used for magical drawings such as when forming talismans.