Basically the gem acts like a medicine. Just as after identifying the right disease and giving the related medicine, the disease is almost certainly eradicated, similarly a weak planet or an unbalanced planet, after wearing a suitable gemstone, ends its weakness and gives proper results.
Although every person should wear gems only after thorough analysis of Birth Chart, but if astrological consultation is not possible due to any particular condition, then not only can you know about your benefic planets based on the criteria set by Astro Terminal. But you can also adopt the suggestion of the concerned gem.