One of the biggest gem-families, there are more kinds of quartz than there are variations in any other family of gems. These are generally hardy, inexpensive gems and they are found in such an array of colors and variations that it's not difficult to find a good gem from this group. The quartz minerals are the most inexpensive and they are either see-through or opaque, or some degree in between. They are not very brilliant and reflect light poorly, but their colors are captivating and making lovely jewelry out of quartz is a simple task. They are reasonably hard, rating 7.5 on the Moh scale, though different kinds of quartz will have different rates of durability.