Chalcedony is a silica-based mineral composed of very finely-woven growths of moganite and quartz. Naturally appearing in shades of white, grey, blue, and brown, samples of carved chalcedony have been found from sources as early as Minoan Crete and first-century Afghanistan. Blue lace agate in particular derives its signature color from traces of copper, iron, and manganese.
Handmade items vary in size, shape, and color when selected randomly (the highest quality items are chosen first). They'll be as beautiful as those in the photos.