Say hello to Citrine, the vibrant golden variety of quartz that showcases hues from a subtle, pale yellow to a charming, deep brownish-orange. It's a radiant gem that never fails to charm with its warm colours and availability. This gemstone is found in a variety of sizes and shapes, from small rounded cabochons to huge flawless gems of thousands of carats, and even in fascinating fantasy cuts that defy traditional gemstone shapes.
When it comes to citrine, a lot of the citrine in today's gem market is a result of heat-treated amethyst, especially the ones that are of deeper yellow and brown colours.
Citrine, deriving its name from the French 'citron' and Latin 'citrus' for its lemon colour, is sometimes misleadingly marketed under other names. Misnomers like "Topaz Quartz" or "Gold Topaz" are often used to enhance its appeal, but the truth is, citrine stands beautifully on its own. The darker, more reddish varieties are referred to as "Madeira Citrine," reminiscent of the rich Madeira wine.
Citrine comes in a variety of colours, from pale yellow, greenish-yellow, yellow-orange to brownish hues, grading into smoky quartz. Certain specific colours even have names of their own. For instance, the deep orange to reddish-browns are called Madeira Citrine, and the lovely golden colours are known as Golden Citrine. Palmeira Citrine refers to the vibrant orange tones obtained by heat-treating amethyst from Brazil's Palmeira Mine.
Most citrine in the market has its colours enhanced through heat treatment, which brings about a richer colour with reddish overtones. However, rare natural citrines bear a pale, greenish-yellow to yellow-orange colour without such reddish hints. In rare cases, smoky quartz with lithium can produce greenish-yellow colours upon gentle heating and is sold as Lemon Quartz, Lime Citrine, or Ouro Verde (Portuguese for Green Gold).
Citrine, particularly the rare natural variety, is found across many countries, including Brazil, Bolivia, Spain, Madagascar, the USA, Zambia, Russia, Norway, and Australia. However, the principal sources of amethyst, which is widely heat-treated to create citrine, are Brazil and Uruguay.
Citrine falls under the broad umbrella of quartz minerals. Its sunny disposition comes from the traces of iron found within its crystalline structure. As a variety of quartz, it shares its crystal system, trigonal, and hardness, rating a solid 7 on the Mohs scale, with its quartz siblings.
Citrine is celebrated as the birthstone for the month of November. It shares this honour with another gem, topaz.
Citrine's rich history dates back to ancient times when it was popularly used in jewellery. Ancient engraved gems, known as intaglios, show evidence of heat treatment, indicating that the process of turning amethyst into citrine may have been in use for more than 2,000 years.
While citrine is readily available and affordably priced, the value can increase based on its colour and clarity. The most sought-after citrine colours are the intense yellows and deep reddish-oranges, particularly those without brownish overtones. Naturally occurring citrine with strong colours is quite rare, making it a prized possession for collectors and gem enthusiasts. It's noteworthy that larger citrines, even those reaching thousands of carats, can be obtained without visible flaws, making the stone exceptionally valuable for its size.
When choosing a citrine, the colour saturation and clarity should be considered. Citrine gems are often eye-clean, meaning they lack inclusions visible to the naked eye. Those formed by heat-treating amethyst can contain the same inclusions as amethyst, such as two-phase inclusions, other minerals, diagnostic tiger-stripes, and repeated twinning. A high-quality citrine has strong golden yellow colour, excellent transparency, and no eye-visible flaws.
The vast majority of citrine in the market has been heat-treated. This treatment usually involves the heating of amethyst or smoky quartz, which contains iron impurities, changing its colour to that of citrine. This colour change can be reversed by irradiation, a fact not known to many. Although all treatments should be disclosed at the point of sale, it doesn't always occur in the market.
Synthetic citrine can be created using hydrothermal methods, where impurities of iron are added to induce an intense colour. These synthetic versions lack the natural inclusions and colour zoning of natural citrine but may have breadcrumb inclusions.
With a hardness of 7 on the Mohs scale, citrine is quite resistant to scratches and daily wear. However, sudden temperature changes may damage the stone. It is best to clean citrine using warm soapy water and a soft brush. Ultrasonic cleaners are generally safe, but steam cleaners should be avoided.
The use of citrine goes back to Roman times when it was fashioned into cabochon, or rounded shapes, and set into rings. Today, it continues to be an essential part of the jewellery world and is seen in various forms, including pendants, earrings, and rings.
Citrine often gets confused with golden-yellow topaz and reddish-orange imperial topaz due to their similar colours. It may also resemble yellow sapphire, golden beryl variety heliodor, yellow scapolite, and yellow apatite. Deep orange to red citrines can sometimes be mistaken for certain types of garnets. However, these can be distinguished by different refractive indices and other optical properties.
As a member of the quartz family, citrine is closely related to other quartz varieties like amethyst, rose quartz, and smoky quartz. It's fascinating to note that amethyst, when heated, can change its colour to citrine's characteristic golden hue.