Board Thread:General Discussion/@comment-25028999-20140801192152/@comment-24986099-20141106004352

The Gem is basically the actual physical body of a Gem because their 'humanoid' bodies are just holograms/illusions.

Most likely the only way to kill a Gem is by destroying their Gemstone (Given the amount of worry the Crystal Gems displayed when Amethyst cracked her Gemstone). Since the rose quartz stone is still in tact, Steven's basically wearing his mother on his stomach.