It would vary a lot between different people. My dad seems to think I'll never commit suicide no matter how much I mention it, my mom used to think the same also although earlier this week on a very bad day for me she slept down in the living room, I'm guessing because she wanted to hear if I sneaked out of the house to commit suicide. I've mentioned I've left the house during the night before planning on this a few times, and she might be doing this again tonight. I'll say an 8 from my dad and a 6 from my mom. I've never told any of my friends about my issues besides a couple of my health issues. One of them has kind of signaled to me he knows something is wrong, just not to what extent. I overheard another talking saying he didn't believe me when I said that I left college for health issues (even though I did) when I just returned and saw him recently, even if he's wrong about the health issues he's right about there being mental issues. I'll say an 8 from both of them. As far as I can tell none of my other friends have ever been aware that I might've ever considered suicide.
I'm sure none of the people in my classes from 7th grade-11th grade would be shocked that I committed suicide I had a reputation for being mentally ill, it was an extremely large school so not everyone knew it but it was still pretty bad. In 12th grade a few weeks before I was planning on committing suicide I had a breakdown in class, I'm not sure how much word of that spread. Also in 12th grade a note saying I was going to kill myself fell out of where I was hiding it or something and people in my class found it later and asked me about that. I straight face denied it. I just paused for a few seconds and said no. I don't know if it worked. I used to be funny back during that grade so people might not have believed it. I made a joke about it to my friends afterwards and they laughed so I know at least they didn't believe it.