Quartz is a huge family of minerals with the same chemical composition and similar properties. It makes up 12% of the earth's crust.
However, in the gem and jewelry trade when someone refers to chalcedony, they are usually talking about a semi-transparent or translucent stone with a solid color (most often soft blue) with a waxy luster. This type of chalcedony can also be white, purple, pink, yellow or red but not orange-red which is referred to as carnelian.
I enjoy making jewelry with all types of quartz from clear rock crystal quartz to the astonishingly colored and patterned jaspers and agates. A few of my current favorites are:
Visit Jewelry Facets to learn more about all the branches of the quartz family as well as a wide variety of other gems and gemstones.
Lynn's musings about all facets of jewelry.