Turquoise is available in a number of finishes. Some of these are a result of human intervention (e.g re-constituted turquoise) and some are natural. While I like the earthy turquoise stones, sometimes a splash of brighter colour is a great addition to a piece of jewelery. The Turquoise Guide (http://www.turquoiseguide.com) reports that this 'reconstituting' method involves grinding turquoise 'trash', mixing it with a powder, pouring it into a mold and drying it. The resulting material is cut into slabs, and then used for making jewelery (or whatever else the buyer wishes to do with it). This material is of lower value than other turquoise. The Turquoise Guide reports that natural turquoise is hard to aquire, and very expensive.
I am currently making a bracelet, in which several different turquoise types are used. These are mixed with lapis lazuli (because with this bracelet I am taking a tilt at the old 'blue and green should never be seen' mantra... the natural world is rich in the blue and green mix, and I find it very pleasing to the eye). Finally, here are some pics... turquoise, aventurine, African jade, lapis lazuli, faceted opalite, blue fresh water pearl and a few beautiful, aqua coloured, faceted Czech crystal cathedral beads. Blue and green are beautiful together!