Buy RS3 Uncut onyx
The uncut onyx is one of the rarest gems in RuneScape 3. Only the hydrix is more rare. It is a shiny black gem used in the Crafting skill to make jewellery. It is a members-only item that is tradeable and noteable.
You need level 72 Crafting and a chisel to cut an uncut onyx into an onyx. Cutting it grants Crafting experience. The cut onyx can then be made into strong jewellery. This includes the onyx ring, onyx necklace, onyx bracelet, and onyx amulet. Each piece can be enchanted. The onyx amulet becomes the Amulet of fury, one of the most popular necklaces in the game. Cutting an onyx can also give 24 onyx bolt tips instead.
The gem has other uses too. With level 90 Divination and an active necromantic crystal, it can be made into a pulsating onyx. It can also be disassembled for materials like precious components and faceted components.
Uncut onyx gems drop from bosses like Araxxi, Telos, Solak, and Nex: Angel of Death. Buying one skips the long grind and gets you crafting top-tier jewellery right away.