Clear Topaz is the original form and name of Mystic Topaz, before she was kidnapped and experimented on by the Homeworld military.
Clear Topaz is significantly more cheerful and expressive pre-experimentation. Her powers are also more stable, and she doesn't show as much as an interest in fiddling with technology as Mystic does. She also had many friends. Clear Topaz was more vulnerable to Homeworld propaganda; it took her a while to accept the harsh truths when she became Mystic Topaz.
Like other Homeworld Gems, her outfit has a diamond on it.
Clear Topaz, also known as White Topaz or Silver Topaz, is a gem that promotes mental clarity. It's also known to promote lifestyle changes, reflecting how Mystic Topaz eventually changed her opinion of Homeworld and felt compelled to escape.