I get this question often, and for good reason — how much privacy will my glass block give me?
The answer is “it depends”. Classic designs such as wave (popular for basements) offer some privacy, but the closer you get to it, the more anyone lurking outside your home will be able to see. If you are as few as 6 inches away, a viewer may not be able to tell how many fingers you are holding up, but would likely be able to tell your skin tone.
If your project is in a bathroom, look for a privacy glass such as ice or diamond. While diamond is quickly becoming a dated design (think mullets and leisure suits), ice has been around for a long time. Even if you’re touching the ice style, a lurker is unlikely to be able to see how many fingers you are holding up. Ice is also good for refracting light so they may not even be able to tell what skin tone you have.
There are some variants on the wave glass that make it even more private.