Ruby

A Ruby is a gem that is used in the crafting skill. The gem is obtained from cutting an uncut ruby and can be made into various pieces of jewelry.

Jewellery
For more details, see Crafting

Rubies can be crafted into rings, necklaces and amulets. However in RuneScape Classic the only useful piece of jewelry is the amulet because no other pieces of jewelry can be enchanted to provide bonuses.