The hardest silicate mineral belongs to these Gemstones have golden, yellow, and brown colors. Topaz is the hardest silicate mineral and one of the hardest Minerals in nature (hardness 8). Its common color is golden brown to yellow.
Significant reserves of yellow topaz crystals are found in Siberia and pink crystals in Russia and blue crystals are found in Ukraine, Brazil, Sri Lanka, and Pakistan.
In Iran, some pegmatite veins of Alvand Granite contain topaz. Its effects have also been observed on the island of Hormuz.