Sz 7 Ring 12.81 CTW London Blue Topaz Ring in 925 Sterling Silver. Center Solitaire stone is upwards of around 12 carats with smaller rounds (12) on sides. Deep Blue Color Saturation. London Blue is a long process of enhancement of White Topaz and is valued because of the Gorgeous color. I have read that there could be a sparsity of white topaz because of using it to create London Blue or Mystic. This ring is new without tags