10mm White Topaz NecklaceTopaz comes in many different hues such as yellow, blue , colorless, green, or the very rare red topaz. Topaz occurs in the igneous rock rhyolite, or granite and is found in tiny cavities within these rocks. It is used in jewerly making, and also has industrial uses because it has a lot of qualities such as heat resistance. Gemstones that are cut can really be valuable.