Colored gemstones can adorn everything from fashion jewelry to engagement and wedding rings. While some gems withstand the rigors of daily wear, others are too fragile, sensitive or easily scratched to bear up under daily stress. The hardness scale that German geologist Friedrich Mohs developed in 1812 features four semi-precious and precious gems at its apex. Choose colored gemstones according to the Mohs hardness scale to find the most durable jewelry for every day wear.
Inexpensive and colorful, quartz gemstones are a 7 on the Mohs hardness scale. This large family of gem-quality minerals includes amethyst, citrine, rose quartz and smoky quartz. Heat treatment and irradiation allow jewelers to produce an even wider spectrum of colorful quartz stones, including blues and greens. All quartz minerals are durable enough to avoid scratching and chipping during daily wear. The mineral is sturdy enough to resist scratching even with steel tools.
Topaz is a semi-precious gem to which Mohs assigned an 8 on his scale of mineral hardness. More brilliant than quartz, topaz predominantly occurs in shades of blue or gold. Pink and brownish-red varieties also appear in nature. Jewelry manufacturers frequently enhance the stones' blue hue with heat treatment, but they remain just as resistant to damage. Topaz is not only hard, it is resistant to chemical corrosives.
Ruby and Sapphire
Sapphires and rubies are crystalline forms of the mineral corundum, given a 9 on the Mohs scale. Rubies and sapphires have the same fundamental chemical makeup -- aluminum oxides with a chemical formula Al2O3 -- but different elemental impurities give them a rainbow of different colors. A ruby is technically nothing more than a special case of sapphire; any color of corundum aside from red is a sapphire, while red corundum is always a ruby. High-quality rubies and sapphires bear large price tags, but sapphires in pink, green and yellow are both affordable and durable. These gems are sturdy enough for setting in jewelry meant to last for a lifetime of everyday wear.
Although jewelry stores sell more colorless diamonds than colorful ones, this extremely durable gem comes in virtually every color. Diamonds of any hue are a 10 on the Mohs hardness scale; they are the toughest gems. A diamond can withstand lifetimes of wear without losing the crisp, sharp edges of its facets or becoming scratched. The vividly colored stones that jewelers term fancy diamonds command equally fancy prices, but diamonds in earthy ochres and browns cost relatively little.
- University of Georgia Geology Department: Hardness of Minerals: The Mohs Scale
- International Colored Gemstone Association: Quartz
- Gemological Institute of America: Topaz
- Ruby and Sapphire; Chapter 5: Inclusions; Richard W. Hughes; Aug. 2008
- The Mineral and Gemstone Kingdom; The Precious Gemstone Diamond; Hershel Friedman
- Photo Credit Comstock/Comstock/Getty Images