To choose a top-quality rough gemstone that has not yet been cut, consider the colour saturation, shape and clarity. A unique colour or colour-play ability, such as found in opals, will show that the finished product will stand out after cutting and polishing. Shape and symmetry will determine whether it can be easily faceted or cabbed into the desired form that is easily mountable for its use, such as in jewellery.
A large rough gem may not yield many smaller pieces if it is irregularly shaped, meaning increased waste during gem cutting.