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How do specialists date antique precious jewellery?

It takes a certain kind of skill and finesse to identify when a piece of jewellery was made.

Most people can appreciate the lustre of beautiful gems, but there’s no denying that the world of fine jewellery is cloaked in mystery — and oftentimes confusion — when it comes to diving into the finer technicalities and characteristics of gems (and we’re not just talking about the 4 C’s).

To help polish our understanding, we’ve tapped jewellery expert Louisa Chan to answer some of our biggest questions about the world of jewellery. In this column, she breaks down the basics of coloured diamonds: from the source of colour to the grade scale, to the common misconception that size is not everything.

I can still recall how clueless I was when I first entered into this profession. My idea of evaluating a piece of jewellery was limited to the quality of the gemstone set on them, whether it was a nicely designed work, and perhaps how it looks when it is worn. When my boss back then casually handed me a mid-century Cartier diamond bracelet and asked me what I thought about it, all I could say was “I think it’s a beauty.” He also asked when I thought it was made. I felt so disconcerted — I could not even manage to observe the signature near the clasp.

The ability to date, or discern the era and period of a piece of jewellery, especially antique and vintage pieces, is the kind of skill and expertise you acquire over years of hands-on experience, as well as a lot of diligent reading and learning, I must admit. If you’re keen to understand more about jewellery pieces and its provenance, I would advise you to focus on the following topics of study.

Materials and cut

By materials, we mean the metal, gemstones and other possible components you can find on a piece of jewellery. We are familiar with silver, gold and platinum as common metals found in jewellery, but the development of metallurgy, or the study and technology of metals, dictates how and when they were used and how prevalent they were in certain time periods — which gives us clues to more accurately date the jewellery piece.

For example, silver-backed with gold, which is called silver-topped gold in the trade, was popular in late-18th to 19th-century jewels, as it was invented to tackle the tarnish of silver-mounted jewellery. Gold is less likely to oxidise, but the jewel can still retain a white metal finish with silver.

Platinum, on the other hand, debuted much later in the early 20th century due to its high melting point. Once a torch was invented to melt and fuse platinum safely and efficiently, its hardness actually made intricate lacework possible in pieces from the Belle Époque.

A typical silver-topped gold and diamond necklace from the 19th century.

Certain types of gemstones were particularly popular at certain times, either due to historical discoveries or powerful patrons at the time. Kunzite, for example, was only discovered and named in the early 20th century. Since its gems are usually large and free from inclusions, it became a popular pink gemstone in modern jewellery of the time.

On the contrary, opal dates back to about 4,000 BC and was found in many antiques. Queen Victoria (1819–1901) was a lover of opals and had a fine collection of opal jewellery that she passed on to her five daughters. This is why opals are found on many Victorian jewels. The Royal Court of Britain at the time was considered a model for fashion for the world. Whatever the royals treasured, the public desired.

Similar to metal, gemstone cuts have also evolved through time. Some of the biggest achievements or changes took place in the 20th century. Let us take the example of the modern round brilliant cut: A style that we are so familiar with nowadays, found on almost every piece of diamond-studded jewellery. This cutting style only came about in 1919, when Marcel Tolkowsky published Diamond Design: A Study of the Reflection and Refraction of Light in Diamond. Moreover, it took many more years for experts to improve his formula and give birth to a perfect brilliant cut. It is, therefore, logical to assume that even jewels from the early Art Deco period could not be set with any 57- or 58-facet round brilliant-cut diamonds, unless it has been reworked or repaired.

The modern round brilliant-cut only came about in 1919, and took many more years to perfect.

Artistic style and movements

We should never forget that jewellery is a form of decorative art, just like fashion, furniture and more, it has been a medium through which artists express and experiment with their aesthetic beliefs.

Indeed, there’s a lot of stylistic jargon in the world of jewellery, some of the most common include words such as Victorian, Art Nouveau, Edwardian, Art Deco, Retro, Mod and so on. Studying the manifestos of all these movements, their tenets, prevailing motifs and materials will surely give you a better idea of how jewellery from those periods was designed, hence identify and date a piece of jewellery successfully.

Whenever possible, immerse yourself in all divisions of art from those times, from the shape of glassware to the pattern on a handkerchief; from drawings on wallpaper, to the form of a doorknob, or the structure of a pavilion. When all these dots eventually connect in your database, you will be able to see a piece of jewellery in a different light, plus be able to date it correctly.

A classic Art Deco ruby plaque brooch by Cartier and an emerald sautoir by Mauboussin from the same period, note how both designs focused on geometry and the minimalistic colour combination.

Reference books and exhibitions

Thumbnails of jewels and their manufacturing date.

For people who love reading stories and relishing beautiful images, jewellery reference books will not disappoint. Truth be told, with limited resources, that’s probably the best way to ‘own’ as many fabulous jewels as possible, don’t you agree? My suggestion is to start with a couple of illustrious and well-known jewellery houses, in order to get a good sense of how the style of jewels had changed in the last century.

These coffee table hardbacks are usually structured chronologically, so you may start somewhere in the late 19th century when the Maison was established, for example, and follow its journey through their signature designs up until the 1970s. Later on, once your collection of books become more complete, try to source for older publications. Some of them come with a complete list and thumbnails in the back which details year of manufacture — making it clear-cut to date a piece of jewellery.

Start your own collection of jewellery reference books

Themed jewellery exhibitions take place from time to time across Europe and in the US, though unfortunately there are fewer in Asia. Often the exhibits are borrowed from their current owners or archives, so it offers a rare opportunity for us to view these treasures up close. Even if you can’t make it to the exhibition in time, fear not, for most of them culminate in very well-curated publications that you can buy and bring home to add to your ever-growing library.

This article first appeared on Lifestyle Asia Hong Kong.

Louisa Chan

Originally trained as an architect and translator, Louisa incidentally entered the world of high jewellery when she was presented with an opportunity to work in the auction business. She is currently a Jewellery Specialist in an international auction house and also an avid collector of vintage costume jewellery.