Apatite: A touch of mystery

Apatite derives its name from the Greek word apate, meaning to deceive – referring to how this gemstone is often confused with other minerals, including the striking Parai´ba tourmaline.

Apatite is a lesser-known gemstone in the world of jewellery. Although the mineral is the most common phosphate material found on Earth, transparent gem-quality apatite is rare. Its chemical composition is quite variable, with most gem apatite being fluor-apatites.

The most common colours of gemstone- quality apatite are green or yellowish- brown, earning it the nickname ‘asparagus stone’.

Other colours of apatite include a range of beautiful blues, purples, pinks, yellows, and even blue-greens, in a captivating neon colour resembling the exceptional Parai´ba tourmaline.

Given the significant price difference between Parai´ba tourmaline and neon blue- green apatite, these vibrant hues are the most sought after, and the rarest.

A commonly seen phenomenon in apatite is cat’s eye – a type of chatoyancy – caused by fine needle-like inclusions. This effect in stones with a deep blue body colour is the rarest and most desired type.

Cat’s eye apatite gemstones are cut en cabochon to highlight the sheen.

With a hardness of 5 on Mohs’ scale, apatite is prone to scratching.

This quality, in addition to its somewhat brittle nature, makes it best suited to necklaces and earrings, rather than pieces of jewellery more exposed to wear.

It is advised to avoid ultrasonic and steam cleaning and instead opt for warm soapy water and a soft toothbrush. As with any softer stone, clean gently.

A combination of three factors – softness, brittleness, and thermal-induced cleaving – make apatite a challenging stone to cut.

Different varieties and colours of apatite are found in different geographical locations, due to varying geochemistry.

World sources include Myanmar (Burma) for blue, blue-green, colourless, and green cat’s eye, Mexico for yellow-greens, and Canada for browns and the bright green variety known as trilliumite.

Brazil is a source for green, blue, and green cat’s eye, Madagascar for light blues, Sri Lanka for blue, green, and yellow cat’s eye, and Tanzania for yellow cat’s eye.

Although incredibly rare, asterism in apatite (known as star apatite) has also been recorded.

Depending on the body colour of the stone, apatite can display some wonderful fluorescence under ultra-violet light, including lilac-pinks, pale mauves and greenish-yellows.

A particularly helpful identification feature in the blue and yellow-green varieties is what’s known as the didymium spectrum of multiple fine absorption lines in the yellow and green, observed with a spectroscope.

Synthetic apatite has been produced, though it is very rare and not commercially available. The first piece submitted to GIA for identification was a colour-change specimen in 2001.

Apatite can be an interesting stone for those who love the microscopic world as it often exhibits a range of interesting inclusions of other mineral species, including haematite and tourmaline.

Often, gemstones may have known imitants designed to resemble them and even deceive buyers – but as suggested in the etymology of apatite, it is often the deceiver itself!

It is not at all uncommon for these gemstones to be confused with a range of other minerals.

With its array of gorgeous and vibrant colours, apatite offers a touch of mystery to a special necklace or set of earrings. Looked after carefully, it can be a budget- conscious option, particularly as an alternative to vivid tourmaline.