This is actually a much more complicated question than that, if by "correct" you mean exact. To get a true and reliable temperature reading, you really need to calibrate your preferred program to account for hardware variances, ambient temperature, and software weaknesses. Just like software rarely reports voltage accurately, it rarely reports temperature accurately either. Click the link below and scroll down to the section on "Calibration" to get an idea of what I mean....

http://www.techpowerup.com/realtemp/docs.php

This is why I generally try not to "toe the line" of TJMax with my oc. If you clock your system so your cores sit right on the edge of "too hot" it's entirely likely they're actually well past the limit much of the time. Keeping it 5-8 degrees below TJMax at most is probably a lot safer.

Either way, though, your chip won't "get ruined" because of running too hot as long as you have the appropriate safeguards in place and turned on. Your chip is designed to shut itself down in the event of serious overheating long before it would actually get ruined. It's the "a little bit too hot" over a long period of time that is more concerning.