A Tiara mould is used in conjunction with a silver bar to make Tiaras in a furnace, via the Crafting skill. A tiara mould can be bought from the Al Kharid crafting store or the Rimmington crafting store for 100 coins.
Tiaras can then be used to make elemental tiaras in the Runecrafting skill, and are a good way of training Runecrafting without the need for talismans. They give 52.5 experience per tiara crafted. A tiara will allow a player to access a runecrafting altar by left-clicking the altar. This makes the tiara more convenient than the talisman, as it gives more space for rune essence. A tiara mould can be found in the Workshop of a Player-owned house.