London Blue Topaz vs. Swiss Blue Topaz: What’s the Difference? This entrancing variety-changing impact makes London Blue Topaz an exciting and profoundly sought-after gemstone. One of the most exciting part of London Blue Topaz is its flexibility. It is utilized in a vast collection of jewelry designs, from primary and exquisite to solid and complex. Its dark blue variety looks dazzling against any metal. It tends to be cut into various shapes and sizes, from exemplary round or oval slices to additional advanced and restless cuts, such as the princess cut or the pear shape.