PRIMARY: TOPAZ - "The stone of the sun and joy"
Topaz, the primary November birthstone, is a semi-precious gemstone that holds a hardness level score of 8.0 on Moh's scale. Topaz is another gemstone that comes in a variety of color, although some colors only come about through human intervention.
Most topazes are naturally yellow or brown, and this is the classic November birthstone color. A few yellow topazes have natural pink highlights, and these are the most valuable. Heating the browner stones turns them reddish-pink, and the yellower stones turn clear; irradiating the latter turns them blue. Mystic topaz is clear topaz with a thin layer of titanium oxide applied to give it iridescence.
Alternate: Citrine - "The golden stone of wealth and optimism"
Citrine, the alternate November birthstone, is a semi-precious gemstone with a hardness score of 7.0. As mentioned in the amethyst section, amethysts become citrine when heated, although the stone also occurs naturally.
Some citrines may actually be mislabeled yellow topazes; it is very difficult to tell the two stones apart visually. The easiest way to tell a quartz (like citrine) from a topaz is to rub a facet with your finger; a topaz will feel slipperier than a quartz.