London Blue Topaz vs. Swiss Blue Topaz: What’s the Difference? 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. The blue shade of this topaz is made by presenting the stone to elevated degrees of intensity, bringing about a profound and rich blue tint that is not normal for some other gemstones. What separates London Blue Topaz from other blue gemstones is its ability to change tone, contingent upon the lighting conditions. In regular sunlight, this gemstone appears as a rich and distinctive blue, while in counterfeit light, it takes on a smoky, practically grayish-blue tint.