Blue chalcedony, like its other colored family of gemstones is quartz and is found in volcanic areas and in ground deposits. It comes in all colors although its most common colors are pale blue, yellow, brown or gray. You can also find chalcedony in white or light tan. Its luster is wax like.
Other chalcedony quartz material is agate, jasper, bloodstone, carnelian, onyx and chrysoprase. Agate has several layers of color that are speckled with spots and it possesses different patterns. Jasper is also speckled and is found in opaque colors of brown, yellow or reddish. Bloodstone is a rich dark green or greenish blue color freckled with red or brown spots. The well liked carnelian is a translucent amber color. Black onyx is very common and popular. It can also be seen with a black base and white layers. Chroysoprase, another favorite, is an apple green color. Some chalcedony is dyed to create more lively color. It is most commonly found in blue, red and pink. As with other gemstones, saturation of color is the most important feature.
Chalcedony is a 7 out of 10 on the Mohs hardness scale. Although the admired blue chalcedony is very common, all chalcedony should be protected from scratches, whacks of the wrist if worn as a ring, and chemicals. This stone should not be cleaned in an ultrasonic because the heat and chemicals can damage the stone.
Most chalcedony is cabochon shaped and as you have learned, comes in a variety of colors. Blue chalcedony is the most common and is an inexpensive stone.
Chalcedony sources can be found all over the world but specific blue chalcedony comes from Nambia and Malawi in Africa.