Birthstone Guide: Rock Crystal for Those Born in April

Julia Griffith FGA DGA EG, gemmology and diamond tutor at Gem-A, reveals the birthstone for April.

Everyone knows that those lucky, April-born souls have been blessed with one of the most prestigious birthstones - diamond. However there are alternative birthstone for this month, such as rock crystal quartz, which is slinking its way into modern jewellery designs. 

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Rock crystal is the purest variety of quartz and is transparent and completely colourless. Its name derives from the Greek term krustallos meaning 'ice' and is sister to colourful varieties such as amethyst and citrine. 

Quartz crystal cluster Tucson. Photo by Julia Griffith. April birthstone.
Quartz crystal cluster Tucson. Image courtesy of Julia Griffith.

Out of the world of gemstones, rock crystal has something extra special to offer, as there is no other containing such a wide variety of attractive inclusions.

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Many may think of 'inclusions' as flaws, however, when viewing the array of possible features that can be available within this gemstone one may change this opinion.

Rutile in quartz. Image courtesy of Julia Griffith. April birthstone
Rutile in quartz. Image courtesy of Julia Griffith.

There is rutilated quartz, tourmalinated quartz, fluorite in quartz, hematite in quartz, gilalite in quartz, pyrite in quartz… the list goes on! These different mineral inclusions add further varieties for rock crystal whilst offering dozens of different looks.

Fluorite in Quartz. Image courtesy of Julia Griffith. April birthstone.
Fluorite in quartz. Image courtesy of Julia Griffith.

As part of the quartz family, rock crystal has a hardness of 7, is reasonably durable and stable for use in jewellery. It can be fashioned as carvings, cabochons or faceted gems. An additional bonus with quartz is that it is readily available in larger sizes and at wallet-friendly prices. 

Large quartz crystals at Tucson. Image courtesy of Julia Griffith. April birthstone.
Large quartz crystals at Tucson. Image courtesy of Julia Griffith.

Transparent rock crystal has been used as an imitation of diamond for centuries, due to the fact they are both colourless. Rock crystal will not be as 'firey' as diamond as it does not disperse the light to the same degree, however, a well-cut rock crystal can be very brilliant with excellent return of white light.

Faceted rock crystals are still used as diamond imitations today, particularly as 'accent stones' in jewellery. Designers may choose to surround a coloured stone with melee-sized rock crystals rather than diamonds, offering affordable price-points to the consumer whilst giving a similar look.

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Quartz is a silica (SiO2) and is the most abundant mineral on Earth and therefore it is mined in many localities throughout the world. Quartz grows as long prismatic crystals with pyramidal points that can occur as single crystals, clusters and geodes - all of which can be very attractive and are commonly used as display pieces or set within jewellery. The largest single crystal recorded was from Itapore, Brazil and measured over 20 feet in length and weighed over 44 tonnes.

The industrial uses for rock crystal quartz outweigh its use in jewellery. It is used within the manufacture of glass, sand, ceramics, brick and abrasives (to name a few) and it is considered one of the world’s most useful natural materials.

Hematite in quartz. Image courtesy of Julia Griffith. April birthstone.
Hematite in quartz. Image courtesy of Julia Griffith.

Since its successful synthesis in the 1950s, synthetic lab-grown quartz is used extensively for the majority of industrial processes and may also be found within the gem trade as fashioned stones. 

Notably, quartz is used in the mechanism of quartz watches (hence the name) and anyone who sells watches will know that quartz movements keep exceptionally accurate time losing only seconds over the life-time of the battery. This is thanks to quartz’s ability to release regular electronic impulses at precise frequencies. This rare property, known as piezoelectricity, is utilised within our GPS equipment, telephones and radios as well as in the mechanism, which triggers the airbags in our cars.

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It is this property, which is thought to be exploited during crystal healing as the energy held within rock crystal is thought to amplify and channel universal energy.

Quartz crystals in Tucson. Image courtesy of Julia Griffith. April birthstone.
Quartz crystals in Tucson. Image courtesy of Julia Griffith.

As awful as I feel for ignoring true gemstone royalty with the diamond; this April we’re celebrating the rock crystal – let it reign! ■

This article was written by Gem-A for the Mar/April 2017 issue of The Jeweller - The magazine of the National Association of Jewellers

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Cover image Tourmaline in quartz. Image courtesy of Julia Griffith.

Understanding Dioptase

Understanding Dioptase

Did you think this might be emerald? You certainly wouldn't be the first to confuse the vibrant green of dioptase with the more recognisable, jewellery-lover's gemstone. Here, Gem-A assistant gemmology tutor, Dr Juliette Hibou FGA, explains more about the history, properties and origins of dioptase, an unusual collector's gem. 

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