Blue topaz round faceted stone is 8mm wide on a strong 3mm wide band flat on the interior and rounded on the exterior. Topaz is November birthstone and in the past the yellow version of topaz was prevalent but that lost popularity and is no longer used in jewelry like before. The blue topaz is today's preference. Topaz comes in all colors but most are clear and then treated. People also substitute blue topaz for the March birthstone aquamarine which is expensive and set in gold normally.