Jet and Jet Jewellery

Jet chess table

Chessboard designed and made by John Sherwood

Some of the finest work manifests itself in the two jet chess tables. Three jet chess boards are known to have been made in Whitby. The Museum owns two (the third has been lost sight of) including that designed and carved by John Sherwood which was begun in 1895 being intended for the Diamond Jubilee of Queen Victoria, but which took four years to complete. It was described at the time as ‘the crowning triumph of the jet age – the most beautiful object of its kind ever made’. This particular board was acquired in 1996 from Mr Robert Murfield in memory of his late wife Martha Cox whose father William Cox was one of the last Whitby jet carvers.

Model of jet workshop

Jet Workshop Model made by George Wood

One of the most interesting artifacts is the replica of the jet workshop model made by George Wood, a jet worker, in 1889. This model stood for many years in the doorway of Elisha Walker’s jet shop at 97 Church Street in Whitby. The heads of the 6 jet workers were carved from the bowls of clay pipes and were caricatures of George Wood’s fellow jet workers. It was driven by clockwork and the men treadle their machines such as polishers, turners, finishers, grinders, working the jet, whilst the foreman’s head turns periodically to see that everyone is working hard! The model was donated to our Museum and was on display for many years but it became too frail and fragile to be left on display. So we commissioned a replica which was made by Alan Dickinson and Gary Thwaites and was generously funded by the Thomas William Varley Roe deceased fund. This replica is a very popular object in the Museum. The original model is kept in store at the Museum.

Whitby Jet mining

Is Whitby Jet Mined?

It is often assumed that collecting jet was a simple matter of picking up fragments from the beach. The reality, both historically and today, is far more complex. Finding usable jet on the beach requires extensive local knowledge of tides, geology, and specific collection sites. The material is unevenly distributed, and even experienced collectors are rarely rewarded on most tides. Fragments found on beaches are typically small, weathered, and unsuitable for larger objects.

Jet must also be distinguished from other similar-looking black materials such as cannel coal, oil shale, and waterlogged peat wood—all of which wash up on the same tide line. This identification requires significant expertise and material knowledge, suggesting that even in prehistory, jet collecting was undertaken by skilled specialists rather than casual beachcombers.

Did the Victorians Mine jet from the Cliffs or Inland?

The scale and variety of jet production during the Victorian era—and indeed throughout history—could not have been sustained by beach collection alone. By 1876, beach-collected supplies were exhausted, and mining became essential.

Victorian miners worked in extremely dangerous conditions, using suspended wooden platforms to access jet seams in the friable mudstone cliffs. Sea-level mines targeting hard jet beneath the Top Jet Dogger—a dolomitic limestone layer—remain visible along the coast between Boulby Cliffs and Ravenscar. Miners sometimes camped on sea ledges to avoid the perilous climbs between tides.

As coastal supplies dwindled, inland mining became crucial. More than 300 jet mines have been recorded within the North York Moors National Park, though many predate formal registration. Unlike coal, jet does not occur in seams but as isolated pieces of fossilised wood, making extraction highly speculative and labour-intensive.

The Hutton Jet Mine Discovery

In 2016, the discovery of the Hutton Lowcross mine—located approximately 23 miles inland from Whitby—revolutionised our understanding of Victorian jet mining. The site contains over 8 kilometres of subterranean passages, some laid out in systematic galleries reminiscent of industrial ironstone operations. Since then, additional large-scale mines have been documented, revealing the true extent and sophistication of inland jet extraction.

The primary extraction technique, known as “dressing,” involved tunnelling below the Top Jet Dogger, collapsing the roof to expose jet-bearing rock, and recovering any jet from the debris. Conditions were incredibly cramped, and the work was physically gruelling—yet it required relatively simple hand tools and deep knowledge of local geology rather than advanced equipment.

Is There Evidence for Ancient Whitby Jet Mining?

While documented jet mines are typically dated to the Victorian period, compelling evidence suggests that mining may have been practised far earlier. In 1870, Victorian miners working near Roseberry Topping encountered around 20 yards of previously disturbed rock before reaching material in situ. They found marks resembling pickaxe work, narrow passages, and jet seams deliberately excavated to their ends—clear evidence of earlier extraction. The area, marked on early Ordnance Survey maps as “Ancient British Settlements,” shows a density of circular depressions more consistent with systematic mining than habitation.

Further evidence includes a Saxon bead now in our archaeology section of the museum, discovered 100 feet into a Victorian mine at Hawsker in 1872, and the hamlet of Jeator Houses near the Victorian Osmotherley mines—”Jeator” being Middle English for “jet miner,” a term documented in North Yorkshire records from the 16th and 17th centuries.

The sheer volume of jet artefacts in the archaeological record—from the Bronze Age boom (22nd–19th century BC) through the Roman period (3rd–5th century AD)—cannot plausibly be explained by beach collection alone. Mining must have played a crucial role throughout jet’s long history.

Is Whitby Jet Mined Today?

Today, jet mining is essentially illegal in Britain. No mining rights for jet have been granted since the early 1900s. The material in the cliffs is owned by private landowners, while the material in the rocks of the wave-cut platform that forms most of the coastal outcrops is owned by the Crown.

However, Turkey maintains an active artisanal jet industry in the Oltu district of Erzurum province, where miners work above 2,200 metres in the Dutlu Mountains. The Turkish mines bear striking similarities to those in Yorkshire, using the same “dressing” technique and relying on naturally resistant rock layers rather than artificial supports. These living practices provide valuable insight into the continuity of traditional jet mining techniques across time and geography. One of our jet curators, Sarah Steele, has visited the Turkish mines and spent time with the miners to better understand how the historical mining operations functioned in North Yorkshire.

Whitby Jet Working

How was Whitby Jet Worked Historically?

Whitby Jet is a relatively soft gemstone, and as a result it requires little in the way of sophisticated tools to achieve a good polish. It’s likely that in prehistory jet was fashioned on hone stones, carved with flint knives, sanded on ‘fish skin sandpaper’ and polished on animal hides with ochre and animal fats. This technique differed little throughout history as evidenced by the Victorian accounts of jet manufacture.

Victorian Whitby Jet Workshop Technology

We are fortunate at the museum to house the work of well-known Victorian photographers such as Frank Meadow Sutcliffe, who captured the jet industry from the mid-1870s. By the early 1830s, mechanical means of turning, cutting and polishing had been introduced to jet working, though the fundamental processes remained remarkably like ancient methods.

A Remarkable Discovery

In 1978, members of the Whitby Literary and Philosophical Society were invited to examine a jet workshop that had recently been revealed in a building in Burns Yard. Evidenced from documentation held in the museum, what they found was extraordinary—a Victorian workshop frozen in time, its contents preserved exactly as they had been left when the last jet worker closed the door for the final time.

The workshop occupied an inverted V-shaped roof space and accessed via a ship’s scuttle-hatch with an almost vertical wooden stairway—a design that maximized working space in the cramped attic. When the hatch was opened it revealed seven treadle-operated machines mounted on high, substantial benches, all still capable of use.

Inside a Victorian Jet Workshop

The workshop contained everything needed for jet production. Boxes of hand-made chisels (mostly formed from old files), circular brushes, lead wheels, and hundreds of pieces of jet in every stage of production—from raw material to semi-shaped pieces, to shaped-but-unpolished items, to completed jewellery. Boxes of rusting hat-pins, ear-rings, and lapidary mountings lay scattered about, alongside masses of spare parts: polishing wheels, cranks, and flywheels of both wooden and iron construction.

Power and Lighting

Rotary power was provided by a simple wooden flywheel about 2 feet 6 inches in diameter and 4 inches thick, mounted on an iron crankshaft. A drive-belt of leather or string connected the flywheel to a pulley on the driven shaft. At floor level, a length of floorboard, pivot-mounted at one end, provided a treadle. A simple connection between the treadle and crank—often just tarry twine—completed the power linkage. Each worker powered their own machine by foot.

Lighting was originally provided by several roof lights, supplemented by old gas pipes running the length of the benches with small, upward-pointing jets branching off to provide additional light at each workplace. By the time of discovery, a single large roof-light remained.

Working Conditions

The whole interior was incredibly dusty. Not only were sheets of paper glued to the inside walls and the outside of the scuttle-hatch, but where the floorboards met the walls, strips of newspaper had been carefully rolled and fitted into the gaps to prevent dust from passing into the room below. This workshop was not unique. A tradesman using an adjoining building explained that many years ago, the ground floor, intermediate level, and upper floor in this building—as well as another workshop in the immediately-adjoining building—were all separate jet workshops. It’s believed that only one man had used the workshop for the last few years of its working life, suggesting this was one of the very last operating jet workshops in Whitby.

This workshop, currently located at 123b Church Street, provides an invaluable window into Victorian manufacturing practices and the skilled craftsmanship that made Whitby Jet world-famous.

Jet in Literature

Alongside the wonderful jet archaeological finds, we have almost 2,500 years of literary evidence relating to jet. Its unusual properties, especially in relation to combustion, became of interest to Greek philosophers in the 4th century BC. The dialogue continues into the Roman period, with Pliny the Elder commonly quoted as the first author on the subject in his Natural History Book 36.34:

“It is black, smooth, light, and porous, differs but little from wood in appearance, is of a brittle nature. When burnt, it gives out a sulphurous smell; and it is a singular fact, that the application of water ignites it, while that of oil quenches it. The fumes of it, burnt, keep serpents at a distance.”

The association of jet with serpents endures to this day and across all jet-working cultures. Pliny, however, was not describing British jet but was in fact describing a material from Lycia, which is modern-day Turkey. This source has never been found and there is some question as to whether Pliny was actually describing jet at all. Solinus, writing in the 3rd century AD, is the first to document British jet, although he draws heavily on Pliny’s description for its attributes. Perhaps the Venerable Bede, writing in the 7th century, is a more reliable early source of information.

Jet has inspired some of history’s greatest minds to write poetry and prose. The following verse was written in the 4th century AD and attributed to Orpheus:

‘…when Jet in rising clouds consumes,
The nose provoking with its pungent fumes.
Black as a coal, but yet of lustrous shine,
It blazes up like a torch of driest pine…’

Other writers have continued to reference jet in their works over the centuries. Perhaps the most well-known of these is William Shakespeare, who is credited with coining the term “jet black” in Henry VI and Titus Andronicus. During the late 1890s, following a holiday to Whitby, Bram Stoker created Whitby’s most iconic figure in the form of Count Dracula. Jet—a material that was once alive but now preserved for all eternity in death – echos Dracula’s vampiric state.

The Victorian jet simulant industry

If imitation is the sincerest form of flattery, then Whitby Jet must be a very desirable material indeed. Over the years, 20-30 different materials, both natural and synthetic, have been passed off as Whitby Jet at one stage or another. Moreover, ‘jet’ is often used as a catch-all term to describe black mourning jewellery in general.

The desire to imitate Whitby Jet has its roots much further back in time than the Victorian era. Modern analytical techniques have shown that Bronze Age neckpieces containing black beads—historically described as Whitby Jet—almost always contain a variety of materials: Whitby Jet certainly, but also oil shales and cannel coals, often within the one piece of jewellery. Whitby Jet is a material where the demand for rough has always outstripped supply in periods of high production, and jet collection requires patience as it is reliant on coastal erosion. We may be seeing, 4,500 years ago, the first examples of Whitby Jet simulants.

The Victorian Simulant Industry

Fast forward to the 19th century and the Whitby Jet simulant market became a fascinating and booming industry. British society was participating in a national obsession with mourning. With the death of George IV in 1830, the Lord Chamberlain’s office dictated the dress code, stating unequivocally that “the ornament shall be jet”. In 1830, the term ‘jet’ meant only one material: Whitby Jet. Demand for rough Whitby Jet was beginning to outstrip supply and other options were needed.

The main attraction of Whitby Jet as a gem material was of course its deep black colour and liquid-like lustre, but more importantly its low specific gravity (SG 1.3). It was fine to look ‘weighed down’ by the convictions of your expression of mourning, but it was practical if the seven strings of beads you wore didn’t weigh more than a few ounces. To be a convincing simulant, the imitation material needed to be light in weight, black in colour, and a poor conductor of heat—Whitby Jet always feels warm to the touch.

Common Victorian Simulants

The Victorian desire to find the perfect simulant led to innovations in materials science—Whitby Jet was in part perhaps responsible for the birth of the modern plastics industry, and therefore the modern world as we know it.

Pressed Horn

In 1712, John O’Bisset discovered that horn could, with the application of heat, be moulded into various shapes. He had discovered the first natural thermoplastic material. With the application of black dye, pressed horn was a good candidate for a simulant of Whitby Jet and many jewellery items were produced. Horn has a tendency to delaminate due to its layered structure, and any damage to the edges gives a slight transparency not seen in Whitby Jet. It is not possible to screw a brooch fitting into jet, so a screw—often seen in horn—is always a sign of a simulant.

Bog Oak

Bog oak is wood that has been buried in a peat bog for thousands of years, gradually turning dark brown to almost black. Items promoting Irish craft traditions had been produced from bog oak in the early 1800s but became popular in the mid-19th century as a cheap substitute for Whitby Jet. Although used for mourning jewellery, bog oak pieces are often carved or stamped with Gaelic motifs such as shamrocks. Concentric rings are usually visible on the reverse of items, and close examination always shows the woody nature of the material.

Vulcanite (Ebonite)

In 1839, Charles Goodyear discovered the method of mixing sulphur with rubber to form vulcanised rubber. With the addition of more sulphur the rubber set hard, could be moulded and was retailed as ‘vulcanite’. Vulcanite was by far the most widely-produced Whitby Jet simulant, used in brooches, bracelets, chains, lockets and necklaces. Vulcanite can be distinguished from jet relatively easily. If the material has been exposed to light over time, it loses its black colour and becomes khaki brown. When rubbed, vulcanite smells strongly of sulphur, and brooch pins are usually screwed into position rather than glued. As vulcanite pieces were often moulded from jet originals, the same designs are seen regularly.

Bois Durci

In 1855, François Charles Lepage secured a French patent for a method of combining blood albumen from slaughterhouses with wood powder to form a mouldable material he called ‘bois durci’. Lepage is reported to have used the marketing strapline “Anything Whitby Jet could do, bois durci could do cheaper and in brown”. The most common items available today are circular plaques showing royalty or statesmen of the time, generally brown and often with ‘Bois durci’ stamped on the reverse.

Celluloid

In the 1860s, John Wesley Hyatt developed celluloid—a semi-synthetic material made from cellulose nitrate and camphor—initially as a substitute for ivory in billiard balls. By the 1870s, celluloid was being produced commercially and became one of the first thermoplastics widely used for jewellery production.

Celluloid could be moulded into intricate shapes and produced in black, making it another popular Whitby Jet simulant. It is lightweight and warm to the touch, sharing some of jet’s desirable properties.

Casein Formaldehyde (Galalith)

In 1899, casein formaldehyde was introduced—a material made from milk curds hardened with formaldehyde, marketed under famous trade names such as Galalith and Lactolith. This early plastic could be produced in various colours including black, making it suitable for jewellery production.

Galalith jewellery was produced in the French jet mills until1930 and sent back to England emulating Whitby Jet, adding another layer to the complex international trade in jet simulants. Unlike earlier simulants, casein formaldehyde represented a new generation of synthetic materials that competed with Whitby Jet not only as imitations of mourning jewellery, but as fashionable modern alternatives.

French Jet and Vauxhall Glass

Glass items were produced in large quantities during the Whitby jet heyday, primarily faceted black glass beads referred to as ‘French jet’. Its higher specific gravity, vitreous lustre and glass moulding marks mean it is unlikely to confuse French jet with Whitby jet. Vauxhall glass—the English version—is thin, highly reflective mirror glass produced by a silvering process, often visible on the reverse.

The Spanish Jet Crisis

Although all the above impacted the Whitby Jet industry, it was a natural jet which was finally responsible for the industry’s decline. By 1870, the Whitby Jet industry reached its peak before catastrophically collapsing.

The final blow was heralded by the arrival from the continent of Spanish jet, first documented in 1874. While Asturias in Spain had some very good quality rough material, it seems that Whitby imported rather poor-quality jet, often containing pyrite, making it unstable. Finished pieces degraded quickly, cracked and crumbled. As a result, consumer confidence in an already struggling product sector collapsed. Beyond the Spanish jet, large volumes of jet were also being imported from France. Documents in the museum collections also attest to the import of a jet-like cannel coal from Venezuela, also retailed as ‘jet’. It’s very likely that other British carvable coals like cannels were also used for larger items.

In 1889, the Whitby Gazette reported: “It would have been better for the Whitby Jet Industry, and better for art development, if the Spanish jet trade had never been known in Whitby.” Despite desperate measures to support the industry, such as a quality mark scheme, it didn’t recover. The mourning trend was well and truly over.

Bakelite —Whitby Jet in the Age of Plastics

The beginning of the 20th century brought a new challenge that would prove insurmountable for the already struggling Whitby Jet industry. In 1907, Leo Baekeland invented the first fully synthetic polymer—phenol formaldehyde—trademarked as Bakelite. The Bakelite Corporation retailed Bakelite as jet until as late as the 1940s.

The struggling Whitby Jet industry was poorly equipped to compete with Bakelite; a new fashionable material marketed as better than the natural material. By this time, mourning jewellery was decidedly out of fashion, and Bakelite represented modernity and the future. It seemed like the end of the road for Whitby Jet.

In 1915, The Lady magazine described the Whitby Jet trade as “A somewhat funereal fetish of fickle fashion”—poor recognition for one of the greatest lapidary trends the world has ever seen. The last man apprenticed to a Victorian jet worker, Joe Lyth, died in 1958, and with him died the secrets of the Victorian era.

Whitby Jet identification and conservation: advisory services for researchers

Whitby Jet Identification and Conservation: Advisory Services for Researchers

As custodian of the largest curated collection of jet and jet-like materials in the world, Whitby Museum maintains specialist expertise in the identification, characterisation, and conservation of carbonaceous gemstones and their simulants. Our jet curators provide professional advisory services to museum collections, heritage organisations, and researchers both nationally and internationally.

Material Identification Services

Accurate species identification is imperative before conservation treatments are applied to artefacts. The complex nature of jet and its numerous historical simulants—including cannel coals, oil shales, semi-synthetic biopolymers, and various jet species from different global localities—requires specialist knowledge for reliable identification.

Our curatorial team employs non-destructive examination techniques and material science expertise to distinguish between true Whitby Jet and simulant materials, including assessment of physical properties, structural characteristics, and diagnostic features.

Conservation Advisory Services

Whitby Museum provides professional guidance on:

• Material identification and authentication
• Condition assessment and risk evaluation for display, storage, or loan
• Preventive conservation recommendations including environmental parameters and handling protocols
• Treatment consultation and material compatibility advice
• Documentation standards including appropriate nomenclature and cataloguing guidance

Research Collections

The Museum’s research collections include Professor J.E. Hemingway’s historical geological samples from his foundational 1933 doctoral thesis, currently under active PhD research at Durham University. Our collections also encompass a comprehensive reference series of Victorian simulant materials for comparative study.

Professional Enquiries

For enquiries regarding jet identification, conservation advice, or research access to our collections, please contact the Museum’s curatorial team with relevant documentation (photographs, condition reports, provenance information) and details of the advisory service required.

Please note: Whitby Museum does not provide commercial valuation services for privately-owned items.

Jet: Frequently Asked Questions

Whitby is known throughout the world for its jet and the Museum holds an outstanding collection. Our curators and staff are frequently asked questions about the collection. The answers to the most common queries can be found below. Please note: Whitby Museum does NOT value personal jet items.

1. What is Jet ?
2. Which rocks contain Whitby Jet?
3. Why did jet form in the Lower Jurassic?
4. Are there different types of jet?
5. How can I tell real Jet ?
6. How has Whitby Jet been used through time?
7. Where can I find further information about Jet?
8. Where can I buy Jet ?
9. How should I care for my Jet ?

What is Jet ?

True jet is defined as fossilised driftwood with a secondary impregnation of bitumen from its surrounding sedimentary environment (Stach et al 1982). Whilst with minor geological adjustments, this model makes sense for the Whitby area, there is currently no consensus among geologists as to the exact processes of jet formation in the geological record.

J.E. Hemingway’s 1933 doctoral thesis, Whitby Jet and its Relation to Upper Lias Sedimentation in the Yorkshire Basin, represents the first systematic scientific investigation of jet and established foundational knowledge that continues to underpin current understanding. We are fortunate to hold many of Hemingway’s research samples within Whitby Museum’s collections, and one of our jet curators is currently working on these samples in her PhD thesis at Durham University, which will provide much clearer insight into how jet is formed in the Whitby area.

Unlike most fossilised wood, jet is formed by ‘jetonisation’ rather than ‘petrification’ of the wood. Jet is therefore preserved as a hydrocarbon rather than being replaced by minerals. Whereas it is far too simplistic to class Whitby Jet as a coal, as the formation process is completely different from most fuel-grade coals, we could perhaps deem it a ‘precious coal’. Despite sharing the combustible properties of coal, there is no evidence that Whitby Jet has ever been used as a commercial fuel—it has been reserved for jewellery and ornamental use.

Is Whitby Jet fossilised monkey puzzle wood?

Online searches will often suggest that Whitby Jet is formed from Monkey Puzzle trees. This claim is frequently perpetuated by the jewellery trade in Whitby as it helps sell jewellery, however it is largely a Victorian myth!

In the early days of geology, antiquarians referred to all fossilised woods as “araucarian materials”. The modern Monkey Puzzle tree, Araucaria araucana, was first introduced to the UK in 1795. It became a fashionable status symbol during the Victorian era due to its unique appearance and ancient heritage, making it a popular addition to British parks and gardens.

As palaeobotany developed, most fossils were assigned to specific species. This did not happen for jet, and hence it remains generically labelled as “araucarian material”. Research conducted by Professor Hemingway on the jet within the Whitby Museum collections identified two distinct species: Dadoxylon gagates and Dadoxylon whitbiensis. Other publications within the collections also suggest that higher-order conifers are involved in the production of jet in the Whitby area. However, as palaeobotanical study can only be carried out on cored jets, we cannot be certain of the species that form jewellery-grade jets. In the jetonised wood, the cells are crushed and distorted, making species identification problematic.

Which rocks contain Whitby Jet?

The Jurassic stratigraphy around Whitby primarily consists of the Lias Group (Lower Jurassic) and the Ravenscar Group (Middle Jurassic), featuring world-famous, fossil-rich mudstones and sandstones. These strata form the cliffs and foreshores, making the area a key location for understanding British Jurassic geology.

The Whitby Mudstone Formation is the most famous formation in the area, particularly the organic-rich “black shales” known regionally as the Alum Shale and Mulgrave Shale members. The rocks are renowned for their exceptional fossils, including ammonites, belemnites, and well-preserved marine reptile skeletons such as ichthyosaurs, plesiosaurs, and teleosaurs, as well as Whitby Jet.

Although the best reserves of jet are found within the historical rock unit known as the “Jet Rock”, jet can be found throughout the Mulgrave Shale Member of the Whitby Mudstone Formation, the Alum Shales, and the Middle Jurassic sandstone sequences above. It is also occasionally reported from the older Ravenscar Group.

Why did jet form in the Lower Jurassic?

Jetonised wood is a rare occurrence geologically, with true jets being restricted to Jurassic and Cretaceous rocks globally. In the Whitby rocks, jet formed during a period of oceanic anoxia—the Toarcian Oceanic Anoxic Event—which led to an extinction event. In these conditions there was very little marine life active on the ocean floor, so the driftwood was not broken down by other organisms.

In these low-oxygen conditions, organisms adapted to such environments thrived, namely bacteria and plankton which produce organic molecules. These organic substances ultimately form North Sea Oil, explaining the oily products found in Whitby Jet. These same conditions are also responsible for the exceptional preservation of other fossils in the Whitby stratigraphy.

Where else in the world is jet found?

Beyond the key European localities of Spain, Germany, Portugal and France—many of which had established jet-working guilds during the medieval and Early Modern periods—Turkey also has an established jet industry which is still active today. True jets have also been utilised in the Americas, with the primary deposits in New Mexico.

Other materials, predominantly coals formed from algae, or the waxy parts of plants deposited in lakes, have been used historically for jewellery production. Today the most significant material is extracted from the Lake Baikal area of Siberia and retailed under the name ‘Siberian jet’. This material is referred to as ‘gagat’ in Russian, a term that translates to ‘jet’ in English. It is not, however, a true jet, and Russian scientists warned that these materials were not genuine jets as early as 1934.

Unfortunately, such materials are still retailed as jet today, and they represent a significant challenge and threat to indigenous jet workers in Whitby and elsewhere.

Are there different types of jet?

Adding to the complexity of jet formation is the fact that we have four different varieties of jet in the Whitby rocks: hard, soft, brittle and cored.

Historically it was assumed that hard jet (the best jewellery quality) formed in marine conditions while the soft variety formed in fresh water. However, this is not the case, as all varieties are found in the same stratigraphy in the Whitby rocks.

Hard jet is always prized for the production of jewellery and ornaments. However, in periods of high demand like Victorian Britain, soft jet was also used, especially for bead production. Over 150 years later, these soft jet items are beginning to fail, with a network of surface cracks appearing that eventually lead to the beads breaking apart.

In cored jet, the wood is incompletely jetonised, with a mineralised ‘core’ in which plant cells are visible in microscopic section.

How can I identify real Whitby Jet ?

Identifying Whitby jet, especially in jewellery items is a specialist task. There are however simple tests that can suggest a genuine piece.

The Streak Test

When rubbed on a piece of fine wet and dry sandpaper (1200 grit as not to damage the jet on an inconspicuous area), Whitby Jet leaves a brown streak. This can vary between a ginger brown for the best hard jet to a chocolate brown of soft jet. As this test is slightly destructive the test must be done on a concealed area. Unfortunately, many other coals also draw brown, and the ‘Siberian jet’ a type of boghead coal will draw within the jet range. This test does however distinguish it from glass which leaves a white streak and fuel grade coals which draw black.

Visual Examination

• Jet is jet-black in colour
• Genuine jet feels like plastic, it is light-weight and warm to the touch, unlike glass
• Signs of moulding indicate an imitation
• Fading in sunlight to a khaki colour is a sure sign of vulcanite
• Screw fittings on brooches indicate horn or vulcanite—jet fittings are always glued
• Chain links in genuine jet show two or three cuts where links have been cut and glued; vulcanite chains show only one or two splits as the link can be twisted to open them when new.

Beware of cheaper imitations often sold as ‘Jet’. Ebonite or vulcanite, bakelite, black glass, coal, epoxy resins and other materials have all been used to imitate Jet. Most of these do not leave a brown streak when rubbed on a piece of unglazed porcelain though ebonite or vulcanite will.

How NOT to Identify Whitby Jet

***⚠️ SAFETY WARNING*** Never use the hot needle test on jet items!

Books and online sources often recommend a ‘hot needle test’ for the identification of jet. This test involves holding a red-hot needle against the jewellery item to burn the surface. It has been reported that burning jet smells like burning coal, which it does. So too do all burning coals and many of the jet simulants, making this test unreliable for identification purposes.

Whereas it is not sensible to inhale the fumes of burning coals or plastics, the main problem here lies in the explosive properties of one jet simulant—celluloid—formed from nitrocellulose, the primary ingredient of modern gunpowder. A hot needle near celluloid could cause serious bodily harm.

Beyond the safety concerns, the hot needle test severely impacts the value of a jet object by causing permanent damage to the surface. If in any doubt, contact the museum for expert advice and identification rather than attempting destructive testing

How has Whitby Jet been used through time?

Jet items are known from the Upper Palaeolithic in mainland Europe, likely used by nomadic Ice Age cultures. Although jet items are known from Neolithic British deposits, the most significant Whitby Jet items from prehistory can be dated to the Early Bronze Age. It is likely that these artefacts were produced in the Whitby area and were traded throughout the British Isles.

Although many Bronze Age artefacts have been excavated from the North York Moors, we only have a small number of jet finds from this period in the Museum’s collections. See our archaeology cabinets for Bronze Age and Iron Age jet finds. It is likely, however, that jet was a valuable high-status material with a value equivalent to gold during the Early Bronze Age.

Jet was likely valued for its mirror-like lustre and potential to hold a static electric charge, a phenomenon known as triboelectricity. Such properties—like magnetism—would likely have been attributed to magic by past populations and explain the importance of jet in the past. Prehistorian Alison Sheridan has described the wearing of jet in prehistory as a type of ‘supernatural power-dressing’.

Jet is seen less frequently in Iron Age deposits as the primary funerary practices changed from burial to cremation. However, the jet finds in the Museum’s archaeology collection from Roxby suggest that jet was still being manufactured in the area during the Iron Age.

Is the Whitby Jet industry still operational?

The last 30 years have seen a revival in the Whitby Jet trade, but with only eight manufacturers currently working in the town, jet-working in Whitby can be considered a critically endangered heritage craft.

Beyond Whitby, Siberian and Chinese coals along with a poor-quality jet material from the Georgian Republic (often referred to as ‘gagat’) are becoming increasingly common as finished contemporary style jewellery and even as antique-style beads from undisclosed sources. Experienced Whitby lapidaries can quickly identify these foreign imposters, but lack of disclosure of origin leads to the material being retailed as Whitby Jet somewhere along the pipeline.

A good Whitby Jet string of Victorian beads is worth £300 upwards; a Georgian imitation is probably nearer £20. Buyer beware!

Where can I buy Jet ?

There are still eight Whitby jet manufacturers working in Whitby today, the vast majority of whom work jet as a cottage industry from premises on Sandgate and Church Street in Whitby’s historic East Side. It is often possible to watch jet manufacturing demonstrations, and the jet workers are happy to answer questions.

How should I care for my Jet ?

Jet can be safely washed in a mild detergent and warm water. It is recommended that moistened cotton wool swabs be used to gently remove any surface dirt. The Jet should then be allowed to dry and then the ‘shine’ can be restored by gently wiping with baby oil. Always keep Jet separate from other jewellery since it is relatively soft and can easily be scratched. It is suggested that each piece should be wrapped in tissue paper to prevent rubbing against other items.

Back to Jet Collection

Further reading on jet