Topaz holds the distinction of being the gem with the widest range of curative powers according to gem lore. Among other things, it reportedly cools tempers, restores sanity, cures asthma, relieves insomnia, and even offsets death.
Topaz, mined in both Africa and Brazil, turns into various colorful blues by a safe two-step process of irradiation & heating. The degree of color depends on the high-energy source used. Heating produces the permanent "London Blue" color of your topaz. Because of its permanent color, no special care is required for blue topaz.
The Gem Junkies dedicated a full podcast episodes to Topaz:
Topaz, Good for Cataracts?