As we enter the dark winter months, November’s birthstone citrine offers rays of warm yellow-orange sunshine. Here, gemmology tutor Lily Faber FGA DGA EG explores the properties and folklore around this sunny gemstone.

Citrine is a type of crystalline quartz that comes in many different hues of yellow, from pale buttercup shades to a stronger orangey or even brown-tinged yellow. Prized for its sunny appearance, citrine has long been popular in the gem and jewellery trade, especially in statement cocktail jewellery.

Citrine Myths and Folklore

For centuries, citrine has been said to hold the power of the sun. The stone is also believed by many to counteract depression and fight back against phobias. Citrine is known as a gemstone that can help its wearer remain calm in stressful situations because of its ability to attract good and positivity. Its characteristic yellow-to-orange colour is caused by a trace of iron in its structure.

Citrine Localities

Did you know? A little-known fact is that lots of citrine offered on the market is often amethyst that has been heat-treated to promote a golden colour. Natural citrine can be difficult to find, despite quartz being one of the most abundant gem minerals in the Earth’s crust.

Part of a citrine crystal. Photography by Henry Mesa, Gem-A. 

This gemstone is found worldwide, but some of the most important localities of note are Brazil, India, Madagascar and Sri Lanka. In Bolivia, amethyst and citrine hues can occur together in the same crystal. These multi-colour gemstones are called ametrine.

Citrine Crystals and Inclusions

Citrine can be found as stand-alone crystals or as a geode containing multiple crystals within a rocky pocket. If sold as an individual crystal, citrine will have a hexagonally shaped prism with a pyramidal termination and slightly thicker base.

Read more: Exploring the Varieties of Quartz

There may be fractures within the crystal that cause iridescence, and the surface may feature striations that run horizontally across the prism faces (if the surfaces have not been polished).

A heated Brazilian citrine of 128.78 carats in a StarBrite cut by John Dyer & Co. Photo courtesy of Priscilla Dyer. 

Inclusions in citrine can be highly variable. However, it mostly has similar inclusions to those in amethyst, such as tiger stripes, straight colour-zoning, incipient fractures (mentioned above), crystals and two-phase inclusions consisting of a liquid and a gas, or a solid crystal and a liquid.

Citrine Care and Caution

Quartz is a 7 on the Mohs scale of hardness, endowing it with the ability to be set into any piece of jewellery, whether it is a ring, necklace or earrings. Considered hard, citrine will resist scratches and abrasions, but it is not impervious to these attacks and care should still be taken when wearing it in everyday life.

Read more: 5 Things to Consider Before Taking the Gem-A Gemmology Foundation Course 

Whether you like its appearance or the meanings behind it, citrine is a fantastic gem that can hold a high polish. This warm, bright and occasionaly overlooked gemstone that can be transformed into stunning pieces that add a touch of sunshine to any jewellery collection.

Read more: What Career Paths Can Trained Gemmologists Take? 

Start your gemmology journey by exploring our Short Courses and Workshops.

Discover more about the history of Gem-A and what makes our world-renowned gemmology education so special, here. 

Cover image: A rough citrine cyrstal specimen in the Gem-A Gemstone & Mineral Collection, photographed by Henry Mesa. 

Chatoyancy is the gemmological name given to the curious optical effect in which a band of light is reflected in certain cabochon-cut gemstones, creating an appearance similar to light bouncing off a cat's eye. Gem-A's Collection Curator, Barbara Kolator FGA DGA explains chatoyancy and highlights some of the many gems in which it can occur.

Chatoyancy is the name given to the ‘cat’s eye’ optical phenomenon which can be seen in certain gemstones. The term ‘chatoyancy’, deriving from the French for ‘shining like a cat’s eye’, denotes the effect that occurs when a bright light is shone onto a rounded, reflective surface and causes light to be reflected back in narrow line perpendicular to the observer’s line of sight. This can be seen by looking at a spool of shiny thread or some cabochon-cut gems.

What Causes Chatoyancy?

Chatoyancy occurs when a band of light is reflected from a series of thin inclusions which are parallel to each other (these may be hollow tubes or needle-like crystals of, for example, rutile or haematite).

 In order to display this effect there must be enough fibres oriented in parallel to the base of the stone. The gemstone also has to be cut as a cabochon to provide the necessary rounded surface for the line of light to be seen.

Read more: The Star of India Sapphire

 As the light moves, or the observer’s eye line moves, the line appears to move too, appearing just like the way a cat’s pupil will look under a bright light.

A chrysoberyl cabochon showing a sharp chatoyant effect. Image by Pat Daly, Gem-A.

 The type of line produced will depend on the types of inclusions; the sharpest, finest line is produced in chrysoberyl, which is the only stone which may actually be called ‘cat’s eye’, without a qualifying species name. Such a stone will possess needle-like inclusions which form an effect known as ‘silk’. As a result, a very definite and sharp chatoyant effect is produced.

Which Gemstones exhibit Chatoyancy?

Many species can exhibit chatoyancy including tourmaline, apatite, beryl, actinolite, demantoid garnet, scapolite, sillimanite and quartz among others but only chrysoberyl can be called simply ‘cat’s eye’, the others must be prefixed by the species name.

Tiger's eye quartz. Image by Pat Daly, Gem-A.

 Chatoyant quartz known as ‘tiger’s eye’ is the only chatoyant gem produced in abundance. It can be found in South Africa and Australia and is particularly popular for use in men’s jewellery.

Cat’s Eye Gems

Cat’s eyes commonly occur in yellow, yellow-brown and greenish-yellow. Some stones, such as cat’s eye alexandrite, can even exhibit colour change which is very rare, extremely expensive and desirable. The chatoyancy is caused by very fine needles which give a bright, sharply defined eye.

A cat's eye alexandrite appearing green in daylight and purple-red under incandescent light. Images by Charlie Bexfield, Gem-A.

 Cat’s eye can also show a mesmerising ‘milk and honey’ effect where one side of the line is milky and the other translucent. As light moves across the surface the bands part and merge like the blinking eye of a cat. This particular effect has led some to believe that the stone possesses supernatural qualities.

Read more: Exploring the Varieties of Quartz

 At 8.5 on the Moh’s scale of hardness, cat’s eye is a hard and durable stone and is especially popular in Japan for men’s jewellery due to its rarity.

 Cat’s eye was also a very popular stone for engagement rings in Victorian times, when it was known as chrysolite. Another old name allocated to this stone is cymophane which means ‘wave’ and ‘appearance’ because of its optical effects.

 Chatoyancy is an interesting and unusual effect worth looking out for to add interest to either a jewellery or mineral collection. What’s more, it doesn’t have to be expensive; actinolite, sillimanite and apatite can be found quite easily, and cat’s eye quartz is very popular and obtainable.

Do you have a passion for gemmology but don't know where to start? Why not consider trying one of our upcoming Introduction workshops?

Interested in developing your knowledge on gemmology? Take a look at our Gemmology Foundation course.

Cover image: A yellow chrysoberyl cabochon showing a cat's eye effect. Image by Pat Daly, Gem-A.