If you are a jewelcrafter of the the appropriate level, "prospecting" should be available at a trainer. Once you learn this ability, it should be in your spellbook, 'p' button I believe. Note that it is separate from the Jewelcrafting button, much like disenchanting is a separate entry from enchanting.
In order to prospect, you take 5 of any one ore, and use prospecting on the stack. This consumes (destroys) the 5 ore, and produces various gem(s) and vendor trash items.