Some insurance policies will require worn jewellery to be regularly checked by a professional jeweller to ensure the security of settings and clasps. This is especially true of high value jewellery that may contain inherently small but valuable single stones. Part of this good management practice can be possible repairs where mounts or clasps may be worn down with regular use or age, and the cleaning of the jewellery to ensure it continues to sparkle and shine or maintain its lustre.
Mohs scale of hardness is a good place to start to understand how jewellery should be cleaned and stored. The harder the substance, the more it can tolerate scrubbing (always gentle) and cleaning agents. Friedrich Mohs was a German geologist who compiled the hardness definitions in 1812. This gives a hardness scale from 0 to 10, with 10 being the hardest. The below table shows some examples of how metals and minerals fit into this scale.
|2.5 – 3.0||gold, silver, aluminium|
|6.0 – 7.0||opal, peridot, tanzanite, jade|
|7.5 – 8.0||emerald, aquamarine|
|8.0||topaz, cubic zirconia|
Cleaning jewellery can be a fairly straightforward process and inexpensive, but the way in which this is done depends on its composition. Careful consideration needs to be given to the metals and stones that make up the piece to be cleaned.
There are old remedies that some people swear by that can be effective for some types of jewellery such as soaking in gin or vodka, scrubbing with toothpaste and even using saliva. The first of these may be effective for some types of jewellery, although not the cheapest liquid solution! Toothpaste is not recommended as it can have abrasive particles in it that are harder than the stone or metal being cleaned. It can cause scratches and a dulling of the surface. Saliva is thought to be effective with some items; it naturally contains enzymes that break down starches that may stick to the jewellery’s surface, but there are more hygienic methods of cleaning that give a deeper clean.
Diamonds are often described as oleophilic which means they attract grease. An effective cleaning method is to use dishwashing liquid with water that is hot, but not too hot to touch. A soft toothbrush used gently will help to remove dirt and grease. This can also apply to sapphires and rubies.
Emeralds are softer, as indicated in Mohs table, and need a gentler approach when being cleaned. They are part of the beryl family which includes aquamarine, morganite, and heliodor (yellow beryl). These should only be briefly cleaned with mild detergent, warm water and a very soft natural bristle brush.
Coral, natural or cultured pearls and opal are regarded as soft and organic gems. These need special attention and a different approach as cleaning products will damage them. They should only be cleaned with a soft dampened cloth and gentle rubbing, then properly dried. Do not submerge a pearl necklace in water as the silk thread connecting them may be stretched and weakened. Coral is an animal product (limestone skeleton) and should be cleaned only with a soft cloth and rinsed in warm soapy water; it should not be soaked. It then needs to be dried thoroughly. Solid opal can be cleaned in warm water and mild detergent with a soft cloth, but doublet or triplet opal (man-made layered opal stone) is completely different and should not be immersed in water. These can be cleaned with a damp soft cloth and mild detergent.
The above comments are all very well if the jewellery piece is not complicated or delicately constructed and is chiefly made up of one type of mineral or metal. But what about if the piece is more intricate? Closed set old settings are unsuitable for cleaning in a liquid, even water. Liquid that gets inside these settings can cause problems with the mounts and any foiled stones, possibly damaging their appearance permanently (foiling refers to the process of backing gemstones with foil to change their colour or appearance). Old jewellery pieces or intricate designs with small stones are best left to expert cleaning available at a jeweller. Cleaning these professionally is money well spent.
Often the best place to store jewellery pieces is in its original packaging box, particularly if the maker is well known. At least each piece should be stored separately in an individual pouch or case. Necklaces, bracelets and other items that contain a clasp mechanism such as watches, should be stored with the clasp closed. This prevents scratching by the catch of the clasp and will reduce the tendency for tangling.
The atmosphere surrounding jewellery needs to be considered. A good hiding place may be desired, but the area should not be too damp or too warm, preventing jewellery damage such as dulled surfaces or cracking of delicate pieces. Organic pieces like pearls and coral need to breathe, so containers that allow some air circulation rather than plastic or sealed storage is best. Never store pearls in cotton wool, for example. Pearls contain moisture and if stored in cotton, this moisture can be drawn out, resulting in cracking. Pearl dealers often store them in silk cloth.
Soft and organic gems (coral and pearls) benefit from regular wearing (fortnightly/monthly) as the natural oils of skin help to keep them moisturised and maintains a good lustre. However, try not to wear with perfumes or scented creams; these can damage their surfaces and lustre, adversely affecting their value. There is an old saying with pearls, ‘last on, first off’. Pearls are alkaline, so contact with any acids such as hairspray and perfumes can damage them. If perfume is being worn, make sure it is dry on the skin before wearing pearls, or better still, wear the perfume away from the area on the body where the pearls will be worn. Vinegar will damage them, and if left for long enough, dissolve them almost completely (yes, the myth is true!). If something acidic is accidentally splashed on them (eg. salad dressing), clean them as quickly as possible.
‘How to clean your jewellery’, Christies.com/features/, 12 June 2020.
‘An Illustrated Dictionary of Jewelry’ by Harold Newman, published by Thames and Hudson.