When opal is found, skill and experience is needed to recover the opal with as little damage to it as possible. In Mintabie, pockets of opal are usually found in hard sandstone. The opal is removed from the ground with much of the sandstone attached to both sides. The opal is usually cut out of the sandstone using diamond saw blades cooled by water. It is then tumbled in an opal tumbler with water to remove more of the sandstone. Before grading and classing, the opal is passed through several sieves to sort the opal into different sized pieces.

The skills involved in grading and pricing of opal are impossible to impart in a written text. Years of looking at many parcels of opal, and an intimate knowledge of the opal markets are pre-requisites of understanding how to value opal. In Mintabie as well as other opal fields, the services of experienced miners are often called upon by miners wanting advice on the value of their parcel of opal. There is usually a price put on this service, but it is worth the peace of mind to know that you have not sold a parcel of opal for less than its true value.