It can be pretty hard to tell if turquoise is stabilized or not, especially for cut and polished cabs. Also, it helps to remember that stabilization is not a singular process but there are several different techniques that change the stone in different ways. For example, a relatively newer technique called the Zachary process can be particularly difficult to identify:
You are right that stones with a very polished, glassy appearance are generally stabilized. However, I’m not necessarily sure that the stone in your Daniel Reeves bracelet is stabilized. Higher grade stones are hard and will take a nice polish which may just be what you are seeing here. And yes, stones that change color and become more green over time can generally be assumed to be unstabilized (But should be differentiated from turquoise that has a more greenish color to begin with).
In general, stabilization will lock out moisture and unstabilized stones will absorb moisture. I’ve heard of a few tests based on this principle: one is to touch the inside of your lip to the stone. If the stone absorbs the moisture and your lip kind of “sticks” to the the stone that can be an indication that it is unstabilized. Another poster on here suggested once that you submerge the whole stone in water for a few hours or overnight–if it absorbs water and darkens that means it is unstabilized; if the color stays the same it is stabilized. Do not soak stones set in jewelry in water as that could cause them to loosen in their settings.
This thread on stabilization is pretty helpful:
Your ring is stellar, it looks like possible #8 turquoise (very desirable). The pitting in the matrix is just part of the character of the stone–I don’t see any reason to be concerned about it. My guess is that this one is unstabilized.