Whitby Jet and Its Substitutes: A Collector's Guide to Victorian Black Jewellery
Genuine Whitby jet is warm to the touch, surprisingly lightweight, and produces a brown streak when scratched against unglazed porcelain. Its Victorian substitutes — French jet, vulcanite, bog oak, and bois durci — each have distinctive properties that betray their identity under examination. This guide explains how to tell them apart, drawing on identification methods from Gem-A and the Whitby Museum's jet specialist, and shows how each material appeared on mourning rings.
What Is Genuine Whitby Jet and Why Was It So Valued?
Whitby jet is fossilised wood from ancient Araucaria trees, found on the Yorkshire coast around Whitby. Its combination of deep black colour, light weight, warm feel, and ability to take a high polish made it the ideal mourning material. The V&A lists it as the premier material for Victorian mourning jewellery, noting that "supplies of jet were not always sufficient for the demand" — which drove the development of substitutes.
Jet could be carved into intricate designs featuring forget-me-nots, ivy, clasped hands, and other mourning symbols. Unlike any substitute, jet also accepted a high polish that produced a soft, warm lustre — different from the brilliant vitreous shine of glass. It could be combined with gold or silver and semi-precious stones, allowing wealthy mourners to display both grief and social status. During the strictest phase of mourning — full mourning — jet was the only acceptable jewellery material, making it essential for every mourning wardrobe.
What Is French Jet and How Can You Identify It?
French jet is black glass with no actual connection to genuine jet beyond its colour. The V&A describes it as "cast glass (French jet or Vauxhall glass)" — one of four principal lower-cost alternatives developed when jet supply could not meet demand. It was manufactured as pressed, moulded, and faceted beads, often in Bohemia and France.
How to Tell French Jet from Genuine Jet
The differences are straightforward once you know what to look for:
| Test | Genuine Jet | French Jet (Glass) |
|---|---|---|
| Weight | Very light (SG 1.19-1.35) | Noticeably heavier |
| Temperature | Warm to touch | Cold to touch |
| Streak test | Brown streak | White streak |
| Surface | Organic grain patterns, soft lustre | Vitreous lustre, may show bubbles or swirl marks |
| Faceting | Cannot hold sharp facets | Often faceted to brilliant effect |
French jet's weight — significantly heavier than genuine jet — is the quickest field test. Pick up a piece of suspected jet: if it feels cold and heavy, it is almost certainly glass.
What Is Vulcanite and Why Was It the Most Convincing Substitute?
Vulcanite (also called ebonite) was the most widely produced Whitby jet substitute. It is vulcanised rubber — natural rubber treated with 25–50% sulphur, a process discovered by Charles Goodyear in 1839. The resulting thermoset material could be moulded into complex shapes impossible to achieve by carving jet, then hardened permanently.
Vulcanite's particular danger to the unwary collector is that it shares jet's two most distinctive properties: it is light and warm to the touch. Unlike French jet, which immediately betrays itself through weight and temperature, vulcanite can pass a casual handling test.
How to Identify Vulcanite
Two reliable tests expose vulcanite. Rubbing the piece briskly produces a sulphur smell — faint but unmistakable. More visibly, vulcanite degrades over time when exposed to light, losing its black colour and developing a khaki brown or sometimes reddish patina. This degradation is irreversible and is the most common way Victorian vulcanite reveals itself in collections today.
Vulcanite was moulded, not carved, so its designs tend to show uniform detail — every petal identical, every leaf precisely replicated. Genuine jet, carved by hand, shows the slight variations of individual craftsmanship. Popular vulcanite designs included elaborate floral wreaths, clasped hands symbolising farewell, and architectural elements like columns and urns — the same mourning vocabulary used on carved jet, but reproduced through industrial moulding rather than hand carving. Browse our collection of antique mourning rings to compare different materials.
What Other Black Materials Were Used?
Bog Oak
Bog oak is ancient wood preserved in Irish peatlands for thousands of years. It was carved into jewellery featuring Irish motifs — harps, shamrocks, and Celtic crosses — combining mourning function with national identity. The V&A notes that "black jewellery met the need to observe mourning but also became fashionable in its own right." Bog oak is identifiable by its lighter brown-black colour and visible wood grain, distinguishing it from jet's uniform deep black.
Bois Durci
Bois durci was patented in 1855 by François Charles Le Page. Made from blood albumen mixed with wood powder from ebony or rosewood, it could be press-moulded into detailed designs. It is rarer than vulcanite and identified by its uniform moulded texture and slightly different surface quality from rubber-based materials.
Black Enamel on Gold
Black enamel — glass fused to a gold surface — predated the jet industry entirely and continued alongside it. Georgian and Victorian mourning rings frequently used black enamel on gold bands, inscribed with the deceased's name and dates. This was a different market from carved jet: enamel rings were precious objects in their own right, combining the black colour required by mourning protocol with the permanence and prestige of gold. The enamel tradition produced some of the finest mourning rings to survive — the Georgian "In Memory Of" bands that remain among the most collectible mourning pieces today.
Gutta-Percha — Or Is It?
Gutta-percha — a rubber-like substance from the sap of Malaysian Palaquium trees, arriving in Britain in 1843 — is consistently listed as a jet substitute in standard references. However, Sarah Caldwell Steele FGA, the Consultant Gemmologist at Whitby Museum and a leading jet specialist, notes that she has never personally encountered gutta-percha in an actual jewellery item. Many pieces attributed to gutta-percha may be misidentified shellac — a distinction that matters for accurate collecting.
How Did Onyx Function Alongside Jet?
Black onyx occupied a different position from jet's substitutes — it was not a cheap alternative but a complementary material with its own mourning associations. Onyx appeared in mourning rings set in gold alongside diamonds and amethysts, particularly during second and half mourning when the strictest jet-only restrictions had relaxed. Where jet was carved as a standalone material, onyx was typically cabochon-cut and set in gold — a precious stone treatment that placed it in a higher price bracket than jet.
The combination of onyx with amethyst — as in this early Victorian ring — illustrates the transition between mourning phases. Black onyx acknowledged continuing grief while amethyst's purple introduced the first colour permitted under half-mourning rules. Browse our onyx rings and Victorian rings to see how these materials appeared across the era.
How Can You Test Whether a Piece Is Genuine Jet?
Gem-A and the Whitby Museum recommend a sequence of non-destructive tests:
- Weight test: Genuine jet is notably light — lighter than any glass, stone, or mineral substitute. If it feels heavy, it is not jet.
- Temperature test: Jet feels warm immediately on handling. Glass and onyx feel cold. Vulcanite also feels warm — so this test alone cannot distinguish jet from vulcanite.
- Smell test: Rubbing vulcanite produces a sulphur smell. Jet does not smell of sulphur.
- Visual inspection: Jet shows organic grain patterns under magnification. Glass shows bubbles or swirl marks. Vulcanite shows uniform moulded surfaces.
- Streak test (requires care): Scratching an inconspicuous area against unglazed porcelain produces a brown streak for jet and a white streak for glass. This test should only be performed on areas that will not be visible.
- Hot needle test (destructive — use with extreme caution): Applying a heated needle to a hidden surface produces a coal-like smell for jet and a sulphur smell for vulcanite. This test leaves a mark and should only be used as a last resort.
For the broader story of British mourning jewellery and the Whitby industry that created demand for all these materials, see our companion article. Explore our complete guide to jewellery eras for more context.
Frequently Asked Questions
How can you tell genuine Whitby jet from French jet?
The quickest test is weight and temperature. Genuine Whitby jet is very lightweight (specific gravity 1.19–1.35) and warm to the touch. French jet (black glass) is noticeably heavier and cold. Under magnification, jet shows organic grain patterns while glass may show bubbles or swirl marks. A streak test produces a brown mark for jet and white for glass.
What is vulcanite mourning jewellery?
Vulcanite is vulcanised rubber containing 25–50% sulphur, discovered by Charles Goodyear in 1839. It was the most widely produced jet substitute because it shared jet's light weight and warmth. It can be identified by a sulphur smell when rubbed and by characteristic browning when exposed to light over time — a degradation that reveals many Victorian vulcanite pieces in collections today.
Was gutta-percha really used in Victorian jewellery?
Gutta-percha is consistently listed as a jet substitute in standard references, but Sarah Caldwell Steele, the jet specialist at Whitby Museum, notes she has never personally encountered it in an actual jewellery item. Many pieces attributed to gutta-percha may be misidentified shellac. Collectors should treat gutta-percha attributions with caution unless confirmed by scientific testing.
What is bog oak jewellery?
Bog oak is ancient wood preserved in Irish peatlands for thousands of years, carved into jewellery featuring Celtic motifs — harps, shamrocks, and Celtic crosses. It served both mourning purposes (as a black material) and broader decorative functions, particularly during Ireland's nineteenth-century cultural revival. The V&A holds a bog oak brooch in Celtic cross form from around 1860.
What is bois durci?
Bois durci was patented in 1855 by François Charles Le Page. Made from blood albumen mixed with wood powder from ebony or rosewood, it was press-moulded into medallions, plaques, and jewellery. It is rarer than vulcanite in surviving collections and identified by its uniform moulded texture and slightly warm feel.
Was black onyx used as a mourning material?
Black onyx was used in mourning jewellery but occupied a higher status than jet substitutes — it was a genuine semi-precious stone set in gold, not a cheap alternative. Onyx appeared particularly during second and half mourning when jet-only restrictions had relaxed, and was frequently combined with amethyst (the designated half-mourning stone) and diamonds in precious ring settings.
Related Reading
- British Mourning Jewellery — the broader tradition that created demand for jet and its substitutes
- Mourning Rings: Love, Loss & Victorian Sentiment — guide to mourning ring types and dating
- The Three Phases of Victorian Mourning — the rules governing which materials were permitted
- Explore our complete guide to jewellery eras — all era guides from ancient to vintage