Aquamarine

In jewellery-care terms, aquamarine is the easier sibling of emerald. Both gems are varieties of beryl, but aquamarine, the blue beryl, is known for having far fewer fissures than emerald, the green beryl. As a result, aquamarine is more durable and, when set in precious metal open-backed settings, can be cleaned in an ultrasonic cleaner. 

Chrysoberyl

Chrysoberyl is a small group of stones. The main variety, chrysoberyl, is a yellowish green or green to brown stone. The presence of many parallel fine needles within the stone can be exploited by cutters to create a cabochon cat’s-eye chrysoberyl, with a bright line of light that moves across the cabochon’s domed surface and looks like a cat’s eye. Cat’s-eye chrysoberyl is a popular variety of the stone. Its cabochon shape can protect it from having chipped edges, but chrysoberyl is a very tough and durable stone regardless of cut.

Alexandrite is a rare colour-change variety of chrysoberyl; it typically shows a red or purplish brown colour in tungsten and candlelight, and green in daylight. Alexandrite is also very durable.

Chrysoberyls are not porous and can be used in ultrasonic cleaners if the stones are in a good condition.

Emerald

Emerald is a very brittle stone and often has many internal fissures. Fissures and inclusions are part of the stone’s character; the insides of emeralds are often referred to as jardins (after the French jardin for garden) because they resemble leafy scenes. 

To protect emeralds from breaking, they are commonly cut as rectangles with clipped corners – giving the characteristic octagonal outline we now know as the emerald cut – to minimise the chance for edges to chip. For the same reason, jewellers often choose to set emeralds in bezel or rub-over settings, with metal wrapping all around the girdle of the stone rather than metal claws at each corner, to protect the stone. The bezel setting may still be open backed, allowing light to pass through the emerald, but it can allow dirt to collect around the stone. Use a small soft brush, like an artist’s paintbrush, to reach into and around the setting when cleaning the emerald.

To increase emerald’s durability, most stones are oiled. This process allows the surface-reaching fractures to be filled with an oil or polymer resin that has a refractive index closer to that of emerald and higher than air, so the fractures become less visible, and the stone is stronger. This treatment is applied to nearly every emerald on the market and has been practised for hundreds of years; it is one of the only gemstone treatments that does not need to be disclosed because it is so ubiquitous.

Cleaning emeralds requires care. Their fractures do not withstand heat, vibration or liquids well, so do not use an ultrasonic cleaner. The ultrasound can cause some fissures to break further and the solvent can remove the oil from the emerald, which decreases the stone’s durability. Similarly, do not leave emeralds to soak in water with detergent or other cleaning products as they may also break down the oil. Instead, wash quickly in mild soapy water, using a brush to reach around settings, and rinse with clean water before drying with a clean cloth.

Remove emerald-set jewellery when doing anything active or impactful, like exercising, washing and gardening. 

Garnet

The garnet family is a big one: there are many varieties of garnet, including almandine, pyrope, spessartine (US spessartite), hessonite, tsavorite and demantoid, ranging from red and pinkish purple to orange and green.

Garnets are typically durable, apart from demantoid, a bright yellowish-green variety, which is brittle and can break more easily, especially at facet edges. Demantoid-set jewellery should not be put in an ultrasonic cleaner, but other garnet-set jewellery without obvious fractures in the stones can be cleaned with ultrasound. 

All garnets should be kept away from chemicals as they will absorb certain acids. Garnets can, however, be cleaned with warm, soapy water and a soft brush. 

Hardstones: Agate, Carnelian, Chalcedony, Jasper, Lapis Lazuli, Malachite, Onyx, Tiger’s Eye

The “hardstones” form a group of stones commonly used as beads, cabochons and carvings; they are often referred to as the “hardstones” because of their use in hardstone inlays on buildings, furniture and objets d’art. In fact, most hardstones are known for their toughness, as opposed to their hardness. They are generally cut as pieces with many smaller crystals tessellated together, which makes it more difficult for them to break cleanly – only a small section may break away, rather than cracks through the whole stone.

Despite the strength of their structure, the crystals’ arrangement may allow chemicals to reach into the stone/rock. The green-banded malachite is very porous and should be kept away from acids and the ultrasonic cleaner. Likewise, the blue-flecked lapis lazuli contains white calcite crystals that strongly react with acid and should be kept away from perfume and hairspray; clean only with water and a cloth.

Agate, carnelian, chalcedony, jasper, onyx and tiger’s eye are varieties of polycrystalline quartz but distinguished by their colours and banded patterns. Many examples are dyed, particularly banded agates to produce luminous blues and pinks, and this dye can be affected by chemical cleaning products. 

Hardstones are prized for their colours and banding, rather than their transparency – many are opaque. Opaque cabochons, cameos and intaglios are commonly set in closed-back settings, which must not be submerged in water, especially not in ultrasonic cleaners. 

Jade: Jadeite and Nephrite

Jadeite and nephrite are two different gems with a similar appearance – though jadeite’s colour range is much broader than that of nephrite – and they are commonly both sold as jade.

Jadeite is a polycrystalline stone with many tiny jadeite crystals grouped together; it is, therefore, very tough because the varied orientations of the crystals impede fractures from travelling too far through the stone. However, tiny fractures are exploited by filling with coloured dye and impregnating with resin or a polymer to improve the jadeite’s colour and durability. These substances can be removed by acids or the vibrations of ultrasonic cleaners. Wash instead with water and mild soap.

Nephrite is not generally dyed, unlike jadeite, yet it still should not be cleaned in an ultrasonic cleaner and should be kept away from acids. Wash in warm, soapy water.

Opal

Many tales surround opal and its propensity to crack and craze; these are not merely legends about luck, but a real consideration when owning opals. 

The shimmering play of colour these stones are prized for helps to explain how we should care for them. Precious opal is formed of microscopic spheres of silica stacked together; as light shines onto these layers, the small gaps between the spheres breaks white light into its constituent, coloured wavelengths, which are absorbed or returned to our eye so that we see patches and bands of blues, greens, pinks, reds and oranges. These gaps between the spheres mean that opal is porous, and it will absorb chemicals it encounters. Therefore, do not put opal near make-up, hairspray, cleaning products and strong soaps; these chemicals could start to break down the structure of the spheres.

Opal can also dehydrate, so avoid leaving your opal jewellery on a sunny dressing table or in a jewellery box stored in a particularly dry and hot location. Dehydrated opals can crack, leading to a crazed appearance.

Clean by wiping opals with a damp or dry cloth. Do not use an ultrasonic cleaner.

Opals are very soft, so avoid wearing opal jewellery when doing activities that might lead to abrasions on the stone. Over time, heavily abraded and worn surfaces will appear dull and the play of colour will be less visible. A more serious intervention for remedying dull opals is to have them unset and polished again. Polishing must be undertaken by a lapidary (stone cutter) and will remove a small proportion of the stone’s weight; it may not be able to help all stones.

Peridot

Peridot is known for its green colour – no other gemstone typically occurs in quite the same green as peridot. It has medium hardness, so avoid knocks and do not clean in an ultrasonic cleaner. Additionally, the hot water and solvent generally used in ultrasonic baths can negatively affect peridot. Clean with warm, not hot, water and a soft brush. Avoid soaps and strong detergents, as peridot is very reactive to chemicals, particularly acids. Keep away from perfume, hairspray and make-up.

Quartz: Amethyst, Citrine, Prasiolite, Rock Crystal, Rose Quartz, Smoky Quartz

Quartz is a fun gem species: its varieties have distinct colours and they grow in large crystals, large enough to be carved into incredible objets d’art – centuries-old rock crystal bowls are testament to the skill of lapidaries. 

Quartz is relatively simple to clean: hot water, soap and a brush will generally do the trick. Ultrasonic cleaners can be used with caution; only put in stones without any visible fractures and that are securely set in jewellery of a good condition. Amethyst, citrine and rock crystal are commonly found set in antique jewellery which, because of its age and years of wear, may be more fragile than some modern jewellery. Assess each jewel individually and gently clean any quartz jewellery you are unsure about.

Ruby and Sapphire

Ruby and sapphire are varieties of the same gem species: corundum. Simply, a ruby is a red sapphire. Corundum is very durable, which is why rubies and sapphires are such a good gemstone choice for rings as we knock our hands so much, often without even noticing. Rubies and sapphires have excellent toughness and are non-porous, so they should be able to withstand much of what daily life throws at them. 

If their settings are open and secure and the jewels are made of precious metals, ruby- and sapphire-set jewellery can be cleaned with an ultrasonic cleaner. Alternatively, you can achieve a relatively deep clean by leaving your jewels to soak in a hot, soapy water for around 10 minutes, before brushing with an old toothbrush, rinsing, and drying with a clean cloth.

Lower value stones are more likely to be heavily fractured and potentially filled with a lead glass or resin to mask the appearance of these fractures. Known treatments should be disclosed by sellers but check for new fractures yourself by holding your stone up to the light. Keep fractured stones away from ultrasonic cleaners.  

Spinel

Spinel is a tough, non-porous stone that is found naturally in many colours. In appearance and durability, it is like sapphire, but it is generally best to avoid cleaning spinel in an ultrasonic cleaner. Instead, spinel jewels with open-backed settings can be soaked in hot, soapy water and cleaned with a soft brush.

Topaz

Topaz is known for its pinks, yellows, blues and the pinkish orange of the famed imperial topaz. Rarely, topaz has been known to fade in colour when often left in strong light for a long time; this situation is more of an issue for retail jewellers and the strong lights they use in their windows, but it is wise not to leave topaz jewels in a sunny space.

Topaz is not tough; it can break easily along its cleavage planes (directions in its crystal structure), so be gentle with topaz jewels, particularly rings that may get knocked. Do not clean in an ultrasonic cleaner, but gentle washing should help.

Tourmaline

The many colours of tourmaline make it a wonderful stone for jewellers to play with in their designs.

It is a relatively tough stone but avoid ultrasonic cleaning. Instead, use a soft cloth and warm water with mild soap. Tourmaline attracts dust, so stones may need wiping regularly in their settings.

Turquoise

Like opal, turquoise can be porous. It should be kept away from chemicals (perfume, hairspray, make-up) that can be absorbed and stain the turquoise, changing its colour from its characteristic blue to a yellower or greener blue. Wipe with a damp or dry cloth to reduce build-up of residue from the skin.

Zircon

Not to be confused with the man-made cubic zirconia, zircon is a gemstone known for its many possible colours and its very high lustre. 

Zircon is, however, a brittle stone. As a result, you may commonly see older zircons set in antique jewellery with chipped or abraded facet edges from years of knocking against each other and other materials. Avoid wearing zircon-set jewellery if it could easily get knocked. Keep your zircon jewels away from other jewels in your jewellery box.

As zircon can relatively easily break, do not put it in an ultrasonic cleaner. Instead, wash in soapy water, brush gently to remove dirt around settings, and dry with a clean cloth.

Zircon is more reactive to light, particularly UV light, than most gemstones, so avoid wearing in sunbeds or other similar conditions.

Speak to our Concierge service for individual advice for your jewellery.

See part 1 for advice on basic care and the dos and don’ts of looking after your jewellery