I love semi-precious stones. They are so varied in colour and character, often streaky and multi-coloured. Modern dying methods can produce wonderful effects too.
Some are fairly expensive (malachite and lapis lazuli for example). Others are on a par with glass beads. They are relatively heavy, so beware of big chunky beads if you don't like weighty jewellery! If you want bulk without the weight, go for wood or plastic beads.
There are lots of shapes and sizes to choose from, from small chips and tiny round beads up to large pendants. Some, like hematite, come in fancy shapes - stars, hearts, cubes etc. Others are generally only available in rounds, ovals or irregular chunks.
Semi-precious stones can be used alone, or mixed with metal or glass beads very successfully. They make fabulous evening-wear and special occasion jewellery.