With turquoise there are several color ranges that come naturally, and in many mines there are several ranges within the mine. Turquoise ranges from almost pure blue, which most famously comes from the Sleeping Beauty Mine in the southwest USA -- to almost neon green, which is also American, and is referred to as "Mojave Turquoise". The most prized Turquoise has always been the bluest, with the least amount of other minerals showing, (that is the black or brown markings, also called matrix). Second are popping colors of what is more traditionally called "turquoise" (which is a softer blue/green color) -- again, less black or matrix is always more prized.
Now ... don't let that be confused with beauty!! There is no doubt that some heavily patterned turquoise is beautiful. Gorgeous even. One of my absolute favorites is leopardskin turquoise -- but it is not considered jewel quality, and if you know what you're looking at, what makes you go "ahhhh" is the pure blue stuff... And no matter what, you want to see vivacious color.
In essence, if you see turquoise with a very moderate to soft coloration, you know it is lesser quality, and might even be "African Turquoise", which is not even turquoise, but a jasper of another type. Buy it and wear it if you like it, but know why is is less expensive than the good stuff!!