no. If anything, and I am aware of gow manipulative this may sound, but telling them how much they matter to you will force them to put a hold on it, or at the very least force them to realize that doing this would hurt someone else, not just themselves. After this interact with them as much as possible, and find out the baseline reason for their impulses. The goal is to bring them back up to happiness. If the reason is something you can affect, such as bad work conditions or bullying, affect it. A life lost can never be regained. If the root is something out of control, then the best thing to do to stop suicide is make as many positive connections between them and everyone else. It will be difficult to help them for a long time, these changes wont be overnight, but they will change.