Let's Talk About Pearls

As a new member of the Temprell Team, I was enrolled onto the NAJ Jewellery Education course. This covers all things from gemstones, to metal types and properties, to how to handle this information within a retail environment. The blogs in this segment will be informative, essay like and specifically cover the topics that I had to write about for my course. I hope you enjoy reading and hopefully learn something as you do!

For as long as we have been adorning our bodies, pearls have always represented the height of sophistication and elegance. But how much do we really know about these enigmatic gems? How are they formed? Why do they range so remarkably in value?

Whether you are looking to buy, or just want more trivia knowledge, let's talk about pearls.

Natural Vs Cultured

Pearls are the only gemstone that is created within a living thing; shellfish. Usually within mussels and oysters, the process begins when a piece of grit or small debris enters the shell. The animal then creates a defence against the ‘irritant’ and produces a secretion that grows layer by layer around it. This secretion is called nacre and is made up of a carbonate mineral known as aragonite. The longer the shell is left untouched, the larger the pearl will be as these layers will continue to build and build until the pearl is removed or the shellfish dies. The lustre of a pearl refers to how the surface of a mineral interacts with light. In pearls, this lustre is created by the light reflecting off of these multiple layers of nacre and is sometimes referred to as the ‘orient of the pearl’.

Cultured pearls are created through a similar process. However, these shellfish will be farmed and an irritant will be manually put inside the shell rather than this occuring in a natural environment. This irritant can be anything from a small bead to a piece of tissue. Sometimes small shaped casts are put in so that once the layers of nacre have formed, they create a recognisable image, such as a buddha. It is worth noting that a cultured pearl has the same shiny lustre as a natural pearl.

Image Source: Crystallography, 27 June 2014

Freshwater Vs Saltwater

Freshwater pearls are created in rivers within freshwater mussels. The mussels produce a thick nacre meaning that freshwater pearls end up being incredibly shiny with a great lustre. One interesting fact about pearls created by mussels is that the older the mussel is, the thicker the layers of nacre produced and therefore the greater the lustre will be. They are substantially less expensive than the saltwater pearl and this is due to the rarity of them. A single mussel can produce up to 30 pearls at one time and when compared to an oyster who can only produce a single pearl at one time, you can see why the price difference can be so vast.

Image Source: FreshwaterBlog, 24 July 2014

This leads me onto saltwater pearls. All of the sought after pearls are saltwater; some examples of these would be Tahitian, Akoya and South Sea pearls. Another reason that saltwater pearls are so much more expensive than freshwater pearls is that they have to be at least 20 years old before they are considered to be of good quality. The nacre on a saltwater pearl is, however, a lot thinner than that of a freshwater pearl. This means that if you are purchasing a saltwater pearl you must make sure that the nacre is thick enough that it will not peel off. It’s also worth noting that saltwater pearls are naturally more round in form than a freshwater pearl.

Image Source: iStock, 24 March 2010

Recognising The Fakes

Imitation pearls are completely separate from all of these other variables, as they simply look like pearls but have nothing similar in the way of chemical makeup nor are they created by a shellfish. They are usually beads made of plastic, glass or sometimes ceramic and then simply painted to give them the illusion of a iridescent lustre. In the USA it is illegal to sell these without obviously labelling them as imitation. However, there are places that will attempt to fool anyone without this knowledge by labelling them with names such as ‘Red Sea Pearl’ or ‘Laguna Pearl’. Therefore, it’s important that you do your research into these things before you buy them thinking that you are getting yourself a bargain; just as with most things in life, if it seems too good to be true, it most likely is. It has become a popular test for imitation pearls that if you rub one against your teeth and it’s rough then it’s real, but if it’s smooth then it is fake. This is due to the structure of the crystalline within a real pearl and how this alters the texture.

Image Source: DiamondBuzz, 15 Jan 2020

How To Look After Your Pearls

When talking about pearls it is important to remember that they are porous unlike many other gemstones, and therefore need to be maintained independently of other jewellery pieces. One of the simplest things you can do to take care of your pearls is to make them the last thing you put on, and the first thing you take off. This prevents things such as perfumes or creams coming into contact with the surface of the pearl as they can be absorbed and affect the lustre of the surface.

Pearls measure as a 3 on Moh’s hardness scale, making them incredibly delicate. This means that it is a good idea to have either a separate space to store your pearls or make sure they are wrapped in a soft fabric before placing it with the rest of your jewellery. This will prevent any of the pearls from getting scratched from metal or other, harder gemstones.

Keeping pearls in a moist environment and wearing them often can prevent them from getting dry. Whilst also wiping them after every wear removes any chemicals or oils that could corrode the surface. Finally I would suggest you taking your pearls to your jeweller maybe once a year to get them to check over the stones and check that your string is still intact and in good quality.

Image below: Dove Grey Baroque Pearl & White Topaz Pendant by Dower & Hall, found at temprell.com

Measuring A Pearl

Unlike many other gemstones, pearls are not measured in carat weight; instead you measure a pearl in millimetres. For a round pearl you will simply have one measurement, but for pearls that are any other shape you will end up with a measurement of length and diameter. It’s commonplace in India to sort round pearls and string them on what’s known as a ‘Bombay Bunch’ where each string is a different size of pearl. This makes it easier for customers and sellers alike to then string the pearls quickly, efficiently and accurately as half of the work has already been completed.

Image Source: Pearls-Wholesale.com

Pearl Shapes

Pearls can come in a variety of different shapes. There are five main forms that a pearl can take. The first and most ideal of these shapes is ‘round’; these pearls should have the same diameter no matter where you take the measurement from. This is the most well known shape of a pearl and it’s the form that most people desire when buying them. Because of this popularity these pearls are more valuable than the majority of their more misshapen counterparts, depending that the size, surface quality and lustre are all the same.

Semi-round pearls are the next best quality. These can appear round, however a pearl expert with a trained eye will be able to tell these apart. Because of these slight differences, these will be less valuable than perfectly round pearls.

The third type is referred to as a ‘drop’ pearl. These are oval or pear shaped pearls; the shapes affinity to a teardrop is where it gets its name. If these pearls are symmetrical with a good lustre and surface quality, these can be very valuable.

The next shape is referred to as ‘circled’ or ‘circle baroque’ and is called so after the observable circles that are formed around the pearl. Visually, they always remind me of a ball being pulled in tight by elastic bands.

Linking from this is our fifth and final shape variety: baroque. These forms are entirely irregular and individual from one another. They are unsymmetrical and, because of this, they are not extremely expensive. This is a great option for people who do not want to spend a lot of money, but also perfect for people who want to create more elaborate, larger designs as they can look very effective when layered.

The shape will change based on how the pearl has formed within the shell. Unlike diamonds where the shape of the stone can be cut to any desired shape, a pearls shape cannot be changed once it has been formed. For this reason, a perfectly round irritant will be placed inside the shellfish when creating cultured pearls in the hopes that the nacre layers will be formed evenly and create a round pearl.

Natural pearls are more likely to have a baroque shape to them, but cultured baroque pearls also exist and these are usually formed using tissue as opposed to a round irritant.

Image Source: JPearl.com

Pearl Colouring

Whilst the most popular and well known shade of pearl is an off white, pearls can come in a variety of different shades. Such shades are: grey, brown, purple, pink, champagne, green and blue, with each of these colours having a wide variety of shade ranges within them. This colouring is dependent on whether they are saltwater or freshwater grown, and also the type of mollusc that they are grown in.

Although we try to have as much control over the growth of these pearls as possible, the colouring of them is usually rather uncontrolled. One major influence as to the end colour of the pearl is the colour of the shell it is grown in. The Tahitian pearl is a great example of this; grown in the ‘Pinctada Margaritifera Oyster’, this pearl replicates the dark colours of the shellfish’s ‘lips’ which run around the very edge of the shell. This is the only known species to create a black pearl and that is reflected in the price you pay for them.

There are instances when a pearl will be dyed to give the desired colour. This can be good for people not wanting to fork out to own fancy coloured pearls, and if done well it does not necessarily decrease the value of the pearl. If done poorly (as goes with any sort of process that changes a gemstone) it will ultimately decrease the value of them, so make sure that if you are looking for an investment to research thoroughly into what you are buying.

Powerful figures throughout the ages have favoured pearls as an accessory due to their rich and adaptable style. It is rumoured that Cleopatra once dissolved a pearl in a glass of wine and drank it, simply to prove that in just one meal she could eat the wealth of an entire nation.

Whilst these days most pearls don't reach prices quite that high, they will always remain one of the most popularly admired gems of all time.