In many ways, jewellery is the most limited of arts. Precious stones and metals are unreliable, recalcitrant base materials with only a few, often nannyish ways of getting them to do the thing you want. The objects you make mustn't be too heavy, unwieldy or scratchy, but they have to be sturdy: as in engineering, all the bits have to stick together. So when the engineers, as they occasionally do, come up with a new way of building, cue much excitement. Designs change, fashions change, even entire markets change.
Take the cultured pearl. In 1905, after decades of experiment and a couple of fairly major setbacks—killer algae, the death of his wife—a Japanese noodle-salesman called Kokichi Mikimoto finally worked out how to prod oysters into making properly round pearls on demand. An industry that had been virtually fished-out leapt back into life, throwing out little balls of nacre like popcorn; the classic string of pearls moved from the preserve of grande dames of the Belle Epoque (when, weight for weight, they cost more than diamonds) to the neck of your average aspirational housewife. Pearl glut duly led to pearl boredom, which jewellers tried to counter by promoting some often only dubiously attractive colours. But it also gave them more raw material to play with: if you want Big Pearls, you can have them.
Jewellers are magpies. They nick ideas to feather their nests. So with lost-wax casting—what Geoffrey Munn, of the jewellery dealers Wartski, calls "an honourable technique of sculpting, which migrated into jewellery". No one knows when the migration, or nicking, began: there are pieces of Asante gold millennia old, cast from beetles. But it's easy enough to spot jewellery made this way. It'll have a sculptural quality, and perhaps some obviously intricate surface detailing. That's mostly down to the method, which involves carving a design in three dimensions—traditionally in wax, though modern jewellers may use resin, foam or even 3D printers—covering it in plaster, then burning out or "losing" the wax over heat before filling the remaining plaster with molten metal. It's hellishly tricky, though. Even the great 16th-century goldsmith Benvenuto Cellini, maker of a stupendous sculpted golden salt cellar, is on record moaning about the difficulties of casting heads.
Specific techniques seem to lead jewellers towards similar uses. The glossy surface of early enamel, like icing on a golden cake, was often used in religious icons, perhaps because it looked so obviously everlasting, with a kind of holy impermeability. But once flux—the addition of borax—was discovered in the ninth century, the medium flowed more satisfactorily across surfaces and into tight spaces, and enamellers abandoned religion for the tinier, more colourful corners of the natural world: the sheen of a flower's petal, the shimmer of a dragonfly's wings. The exception was Fabergé's beloved guilloché—his own invention of pouring translucent enamel over engraved gold—which instead mimicked the effect of moiré silk, a furnishing fabric used to gussy up walls and chairs. Hence his famous, if rather pointless, eggs: jewellery for mantelpieces.
My own favourite technological breakthrough is all about accessibility. In the 18th century an Alsatian jeweller called Georg Strass began experimenting with the recipe for glass, mixing silica with high levels of lead oxide and additives such as potassium in a wet "paste" before firing. The results were unusually hard and clear, and could be cut, polished and backed with metal foil like real diamonds, at the time themselves backed with foil in an attempt to increase their glitter. But Strass's paste was more malleable than diamond; his gems could be bigger, and cut to any shape, so they could be set very closely together. A Strass paste jewel gave you more sparkle per square inch, and per pound spent—just what the new industrial merchant class wanted. You could argue this was the beginning of the democratising of jewellery, and its design: the unlimited palette of colours, the lightness and fluidity of the material, took the brakes off. As Carmen Busquets, who buys jewellery for the luxury retailer Couturelab, says, "paste jewellery tends to be bold, more colourful and less conformist than traditional pieces. That's what makes it appealing."
None of the jewellery below is particularly conformist, but all of it speaks particularly clearly of the processes, the chemistry and the engineering, involved. And if it's largely way beyond the means of most of us—well, thanks to Herr Strass and his lead additives, there's always paste.
LASER WELDING NECKLACE TOM RUCKER (above)
The German-born, London-based jeweller Tom Rucker can fairly claim to have invented the newest technique here. In 1995 he heard that a Munich-based engineering company was building a machine that could fuse metals using lasers. Before you could say spot-weld he was round there giving what he calls "advice on the design application of such a technology". Two years later he bought the first model off the production line, and soon after ran a course introducing a generation of jewellers to the laser. Many of them would use it simply for repairs, but Rucker is adamant it's "far too good a technique to waste on resizing rings". His excitement is more understandable when you learn that as a young man he wanted to be an architect—"but I was too stupid"—as now he could fuse platinum in structures of architectural complexity, while butting diamonds right up to the joints without danger of cracking. The results combine ethereal airiness with precision and strength, but demand enormous patience: a piece like this, with at least 700,000 welds, can take up to 18 months to complete.
From £38,000; tomrucker.co.uk
LOST-WAX CASTING BROOCH JACK DU ROSE
In a baggy black T-shirt and with large, gentle hands, Jack du Rose, 30, looks more like a friendly bear than a couture jeweller; he keeps snakes and other "dangerous pets" at home and could, in another life, have fitted in well with your local pub band. Instead he's spent the eight years since he left university teaching himself to make jewellery of the most ambitious, and expensive, kind (despite only getting a D in GCSE Art). This 10cm long, blackened palladium, gold, diamond and enamel brooch is part of his first collection, and was cast in sections before being pieced together. The modelling/casting process is crucial, he says, to the design of such large pieces: "I need to hold what I've drawn as a solid object, to see the problems, the visual balance. Often the first model I make won't be right, then I'll start all over again. You can't risk making a piece as complex as this in precious metals without holding the design in your hands first, and that's where the casting comes in."
THE IDEAL CUT EARRINGS CHOPARD
Before 1919, the art of cutting diamonds was just that: more art than science. A diamond crystal would be "cleaved"—a nicely biblical word for the act of bashing it to bits with a hammer and a big iron blade—rubbed down into a roughly round shape using another diamond on the end of a stick, then polished with a disc coated with diamond dust. The results were characterful, but —to the modern eye—oddly dull. It was the Belgian diamond cutter Marcel Tolkowsky who in 1919 applied the science of optics to his craft. He came up with a specific number of facets, and the angles they should be set at, that maximised both the amount of white light escaping upwards from a stone, and the amount of coloured light it reflected internally—what jewellers call brilliance and fire, and everyone else calls bling. Add the coincident explosion of domestic electric light, and the stage was set for the age of sparkle: jewellery, like these diamond-packed starburst earrings, that embodies the Liz Taylor flash-factor.
ENAMEL PENDANT BENTLEY & SKINNER
Enamelling—melting ground zinc, sand or rock crystal with powdered pigments and some kind of alkali (perhaps potassium from wood ash, or dried seaweed), then pouring onto a metal backing—has been around since the Mycenaeans in 1,200BC. But it only really grabbed the human imagination once the Egyptians learnt to refine and purify gold, and hence raise its melting point—since now you could coat your piece of precious gold jewellery with hot liquid glass without the whole thing flopping to a puddle. The real point of the technique, though, is the palette. Enamellists have always loved colour: they use much the same pigments, and experience the same excitements, as painters. This vintage American Art Nouveau brooch shows just how tenderly enamel can attempt natural forms. Yes, it's prettified with dewdrops of pearls, but really they're just the curtain-raiser to the main event: the watercolour shading on those petals.
CULTURED PEARLS NECKLACE MIKIMOTO
Cultured pearls have borrowed souls: at their core is a spherical scrap of polished mussel shell. It's this, together with a sliver of shellfish mantle tissue, that pearl farmers slip into a host oyster using nothing more than a tiny metal spoon and their own dexterity. Two years later—two years of hanging around in baskets in warm seas—the oysters will be cropped. Although a process not without risks—oysters are fussy, bordering on neurotic, about their surroundings—culturing pearls allows for a steady supply of raw materials. And without that, pieces like this gold and white pearl necklace (above left) would never get off the drawing board.
GRANULATION RING ELIZABETH GAGE
Elizabeth Gage's ring has a distinctly archaeological feel. This makes sense when you realise the technique she's used is granulation, the fusing of minute grains of gold onto a larger gold surface, first mastered by the Etruscans. Etruscan granulation at its finest has a captivating, frosted-sunlight effect, but the method was lost in the west during the Middle Ages. Only in the 20th century did metallurgists work out the ancients' chemistry—they lowered the melting point of gold by reducing copper acetate with the carbon in burnt fish glue. You did ask.
PASTE RING LEGGE & BRAINE
Kate Braine and Charlotte Legge are a pair of London jewellers who specialise in glass. "It's so versatile a medium," Legge says. "You can make patterns with it, put foil inside it, magnify things or change perspective." Much like Strass, they choose to set their fired glass "gems" in precious metal, partly for the glitter-factor but also because "it feels more reliable". This ring is typical in its zippy use of colour: "the combinations you can achieve, the intensity are better than real. If an emerald was as green as one of our rings, you would fall over."
Around £600; leggeandbraine.com