Quartz is the ideal gemstone for jewellery and is one of the few coloured stones you’ll find in almost any jewellery shop.
Quartz is a major component of granite and other igneous rocks. It is also common in sedimentary rocks and is a common component of metamorphic rocks.
Well-formed crystals can reach incredible sizes, often exceeding several metres in length and weighing over a hundred kilograms.
The best quality crystals are destined for the optical, electronic and instrument industries (considered the largest consumers), while the lower quality crystals are destined for industry in general (abrasives, ceramics, metallurgy).
Quartz is the second most abundant mineral on earth, found in 12% of the planet, in countries such as Brazil, Madagascar, the United States and others.
Because of its abundance, quartz crystal has many uses in society. As well as being used in jewellery, it can be found in cosmetics, watches, computers, radios and even in construction.
Quartz is a silicon oxide (SiO2) and occurs in nature in polymorphous forms: quartz, tridymite and cristobalite.
As the temperature changes, phase transformations occur, each of which has a specific name.
Pedra de Quartzo - Caracteristicas, Cores e Variedades
Quartz has properties that remain constant over time and has a hardness of 7 out of 10 on the Mohs scale.
This means that it is very resistant to drops and scratches.
Its lustre is generally vitreous, which gives the stone a beautiful sheen. When used in jewellery, the result is a delicate and certainly enchanting piece.
The states of Bahia, Minas Gerais, Goiás, Paraná, Rio de Janeiro, São Paulo and Santa Catarina stand out in the production of crystal quartz.
The stone is usually white or colourless. However, it can have different colours depending on the impurities present in its formation.
Quartz is the ideal gemstone for jewellery.
It is readily available and very affordable.
Even large stones can be bought at excellent prices. Quartz is also one of the few coloured stones you’ll find in almost any jewellery shop.
Amethyst and citrine are the official birthstones and are often used in birthstone jewellery.
As most quartz is untreated, there are many astrological uses for different types of quartz gemstones (such as carnelian), so you can find many planetary jewellery designs using quartz.
Quartz is also often used to make fine watches, including bezels and moving parts.
Quartz is durable enough to be worn every day in quartz gemstone rings and is also ideal for any other jewellery application.
Quartz gemstones can be worn by both men and women as they come in almost every colour imaginable.
You can find quartz in every style of cut and shape, from cabochons to faceted stones, as well as tumbled and pierced beads.
Quartz is also often carved into interesting ornamental designs such as paperweights, animal sculptures or as seals, carvings and badges.
There are two main types of quartz, which can be further subdivided into more specific variety names.
There are two main types of quartz
1. macrocrystalline
Macrocrystalline quartz includes amethyst, rock crystal, blue quartz, citrine, hawk’s eye, prasiolite, cat’s eye quartz, smoky quartz, rose quartz and tiger’s eye.
Macrocrystalline quartz is typically transparent to translucent and forms larger crystals than cryptocrystalline quartz.
2. Cryptocrystalline
Cryptocrystalline quartz forms microscopically small crystals, which in most cases cannot be seen even under magnification. Cryptocrystalline quartz mixed with moganite, a polymorph of quartz, is called chalcedony.
Chalcedony actually includes a wide variety of quartz gemstones, including agate, chrysoprase, hematite, jasper and carnelian. Chalcedony ‘in the strict sense’ usually refers only to lighter, single-coloured chalcedony, usually bluish in colour.
Cryptocrystalline quartz is generally opaque or translucent in clarity.
Quartz Stone
1. Colours and crystal types
The colour of macrocrystalline quartz is as variable as the spectrum, but clear quartz is by far the most common colour, followed by white or cloudy quartz.
Violet (amethyst), pink (rose quartz), grey or brown to black (smoky quartz) are also common.
Cryptocrystalline quartz varieties can be multicoloured. Under artificial light, quartz does not have a desirable quality. It looks best in daylight, especially after sunrise and just before sunset. The deep colours are the most valuable.
There are many different types of quartz crystals found in nature. We have selected the main ones below:
- Colourless quartz: the most common, also called rock crystal;
- Amethyst: this is purple or violet quartz, whose colour is due to the presence of iron or manganese ions in its composition;
- Rose quartz: this is the second most common type, with various shades of pink due to the presence of titanium impurities in the stone;
- Smoky quartz: has a certain amount of aluminium in its composition, resulting in colours ranging from yellow to dark brown, almost black;
- Citrine: has a pale yellow, orange or reddish colour, which can be natural or the result of heat treatment of the amethyst;
- Milky Quartz: has a white colour and is more opaque, giving it a milky appearance, which is actually the result of tiny inclusions;
- Agate: this is a cryptocrystalline variety of quartz, i.e. made up of minerals so fine that they cannot be identified even under a microscope.
Amethyst is a purple variety of quartz and is the most valuable and prized variety. Its purple colour is usually caused by impurities of iron or manganese compounds.
2. Clarity and brilliance
Fine quartz is transparent, which means that light passes through the stone unhindered.
In translucent quartz, the passage of light through the stone is slightly reduced. The best quality quartz is “clean”, free from inclusions of any kind.
As quartz is abundant, there is little reason to select stones with visible inclusions, except those that define the character of the stone (e.g. cat’s eye, hawk’s eye or landscape stones).
Luster is vitreous to vitreous like crystals, while cryptocrystalline forms are generally waxy to opaque, but may be vitreous.
Crystals are transparent to translucent; cryptocrystalline forms are usually translucent or opaque.
3. Cutting and shaping
Due to the roughness of the colour distribution in crystals, quartz is often cut into bright circles to maximise the colour.
Other cuts can be used if the colour is better distributed.
Quartz is available in a wide range of sizes and calibrated shapes, including many sophisticated shapes.
4. Treatment
Colourless quartz is always untreated.
Coloured stones may occasionally be enhanced by the use of dyes (as in the case of agate), irradiation (bombardment with low levels of radioactivity) or heating.
Some stones can also be impregnated or coated with wax, transparent resin or even foil to enhance colour, lustre and stability.
Synthetic quartz is also widely available. Naturally coloured quartz generally shows colour zoning.
5. How to care for your jewellery
- Quartz jewellery doesn’t need complicated care. For example, it should only be cleaned under running water and dried with a soft cloth.
- You should also avoid exposing your pieces to direct sunlight and take care not to drop or knock them.
- If you keep these points in mind, you’ll have beautiful, long-lasting quartz jewellery.
Synthetic Quartz
Synthetic quartz is often found in colours that do not occur naturally. In many cases, the colour is simply too vivid and intense to be a natural occurrence.
