London Blue Topaz: Discover the Magic London Blue Topaz is a gemstone that enthralls the eye with its intense, rich blue tone suggestive of the waters of the Thames Stream that breezes its direction through the core of London. This gemstone is a sought-after treasure among collectors and jewelry enthusiasts, valued for its dazzling excellence and uniqueness. The London Blue Topaz is an individual from the Topaz family, a mineral made of aluminum and fluorine. It is a hard stone, with a rating of 8 on the Mohs scale of hardness, making it a sturdy and enduring gemstone that can be worn long into the future.