Blue is one of my favorite colors. And my favorite gemstone used to be sapphires because of their velvet-y blue color, but in recent years I've grown to love London blue topaz.
A symbol of strength and intelligence, topaz derives its name from Topazios, an island in the Red Sea that is known today as Zabargad. The Greek word "topazios" means "to seek," since the island was covered with a thick fog and difficult to find. Gemstones found on the island were called topaz, although the stones were eventually found to actually be peridot. The real gem of topaz is found throughout the world, with different occurrences producing specific colors. Topaz has several variations, such as, "sky blue topaz," "Swiss blue topaz" and "London blue topaz" which all refer to the darkness of the gemstone. "Sky blue topaz" is the lightest in color while "London blue topaz" is the darkest in color.
However, none of these are naturally occurring colors. Blue topaz, London blue especially, as become controversial in recent years because the color was created by irradiation. Many gemstones, including diamonds, are treated to nuclear radiation to create new, more intense rare colors.
May jewelers were forced to pull blue topaz out of their stores and are still leery of working with the stone. The lighter blue colors have made a comeback recently, but it is still hard to find London Blue which is my favorite.
I recently got a London Blue ring and I just love it. It's a very striking blue because it has a real true blue depth to it, unlike a sapphire which can often be too dark.
If you've ever read the Dragonsinger books of Anne McCaffery, the harpers wear a color called "harper blue". I've always looked for what I felt that color was. London blue topaz is that color.