Citrine is one of two birthstones for November (the other November birthstone is topaz). It is the transparent yellow to brownish orange variety of quartz. Citrines range from light, lemon yellow to “Madeira,” a rich, orange color with red flashes. Today, most of the citrine in the marketplace results from the heat treatment of amethyst. With its ready availability in a broad range of sizes, citrine is one of the most affordable and desired yellow gemstones.
Mining actually yields very little citrine. The vast majority of citrine on the market is produced by heating smoky quartz (which produces light to medium yellows) and amethyst (which produces stronger yellows and orange-red to orangey brown shades). This is stable treatment. Natural stones usually occur in pale yellow colors, often with smoky tones.
Citrine has a hardness of 7 with good toughness and is durable enough for everyday wear and tear.
Topaz is one of the birthstones for November (the other November birthstone is citrine). The variety of topaz hues include colorless, light blue, yellow, orange, pink, violet, brown and red (rare). Precious topaz is currently used to refer to stones with a rich yellow to a medium, peachy orange color. Imperial topaz usually refers to stones with a very saturated reddish orange color.
Topaz is commonly heated to change some of the yellow and reddish brown topaz to create pink gems. The vast majority of blue topaz sold today is the permanent result of treating colorless topaz with irradiation and heating. Another form of treatment common to topaz is surface coating, which results in many colors. The rainbow effect seen in “Mystic Topaz” is created by coating colorless topaz with a thin artificial film. Passion topaz is created by subjecting white topaz to a thermal process that results in a hard ceramic top. The vibrant colors that result include names such as Rainforest, Poppy, Teal, Paraiba, Blazing Red and Poppy that are stable and permanent.
Minas Gerais, a state in Brazil, is one of the most important sources for high-quality topaz, which has been mined there for more than two centuries. Yellow to orange, red, pink, violet and blends of red with orange or purple are some of the colors unearthed here. Other major sources of topaz include Namibia, Nigeria, Madagascar, Mexico, Myanmar, Sri Lanka and the United States, as well as the historic Russian localities.
Topaz is a fairly durable gemstone with a hardness of 8.0 on the Mohs Hardness Scale. Treated gemstones should be protected from surface abrasion.