Amber is fossilised tree resin, an organic gemstone formed over millions of years through the polymerisation and oxidation of plant exudates. Unlike most gems, which are minerals crystallised from inorganic matter, amber is biological in origin — the hardened secretion of ancient coniferous and flowering trees that has survived geological time largely intact. It is among the oldest materials used for personal adornment, with worked amber beads documented from Mesolithic sites in northern Europe dating to around 8000 BCE. Today it remains one of the most widely collected and studied organic gems, prized equally for its warm, resinous colours, its extraordinary capacity to preserve prehistoric life as inclusions, and its long cultural history across civilisations from the Baltic to East Asia.

Formation and Geological Age

The transformation of fresh tree resin into amber proceeds in two broad stages. First, volatile terpenes evaporate and the resin undergoes initial hardening into a semi-stable intermediate material known as copal. Copal, which may be only thousands to a few hundred thousand years old, is sometimes sold as amber but is chemically and physically distinct: it remains soluble in organic solvents, softens readily with heat, and lacks the full polymerisation of true amber. True amber requires burial under sediment, sustained heat, and geological time — generally accepted as a minimum of one million years, though most commercially significant ambers are considerably older.

Baltic amber, the world's most abundant source, was produced by a now-extinct conifer of the genus Pinus (or a closely related genus, debated in the literature as Pinus succinifera) during the Eocene epoch, approximately 34–48 million years ago. Dominican amber derives primarily from the leguminous tree Hymenaea protera and dates to the Miocene, roughly 15–20 million years ago. Burmese amber, known in the trade as burmite, is substantially older — Cretaceous in age, with radiometric dating placing it at approximately 99 million years, making it one of the most scientifically significant ambers for palaeontological research. Mexican amber, from the state of Chiapas, is also of Miocene age and shares botanical affinities with Dominican amber, both deriving from Hymenaea-related species.

Physical and Chemical Properties

Amber is an amorphous solid — it possesses no crystal structure — and its physical properties reflect its organic, polymeric nature. Key constants are as follows:

• Hardness: 2–2.5 on the Mohs scale, making it soft and easily scratched by metal tools or abrasives.
• Specific gravity: 1.05–1.10, exceptionally low for a gem material. This allows amber to float in a saturated salt solution (approximately 10 parts salt to 100 parts water), a simple and reliable field test that distinguishes it from most simulants, including glass and most plastics.
• Refractive index: approximately 1.539–1.545, singly refractive (isotropic) owing to its amorphous structure.
• Lustre: resinous.
• Fracture: conchoidal.
• Fluorescence: typically blue-white to yellow-green under long-wave ultraviolet light, a useful diagnostic property.
• Solubility: insoluble in water; partially soluble in alcohol and organic solvents — a key distinction from copal, which dissolves more readily.
• Electrostatic property: amber becomes negatively charged when rubbed with a cloth, attracting small particles of paper or dust. This property was noted by the ancient Greeks, and the Greek word for amber, elektron, gave rise to the modern word electricity.

Chemically, Baltic amber is characterised by a high content of succinic acid (3–8%), which is largely absent in most other ambers. This has led to Baltic amber being termed succinite in scientific literature, and succinic acid content is one of the principal chemical markers used by gemmological laboratories to distinguish Baltic amber from other sources and from simulants.

Colour and Optical Varieties

The colour range of amber is broader than its popular golden-yellow image suggests. The spectrum runs from near-colourless and pale lemon yellow through the classic honey and cognac tones, into deep orange, red, brown, and occasionally near-black. Green amber occurs naturally, particularly from Baltic deposits, though much green amber in the market has been colour-enhanced by heating in an oxygen-reduced environment. White or "bony" amber results from the presence of numerous microscopic gas bubbles that scatter light and reduce transparency; this variety, sometimes called osseous or fatty amber, is less prized for jewellery but has been used in carving.

The most commercially significant colour variant is blue amber, found almost exclusively in the Dominican Republic and, to a lesser extent, in Mexico and Indonesia. Dominican blue amber displays a remarkable optical phenomenon: under transmitted light it appears the same golden-yellow as ordinary amber, but under reflected daylight or ultraviolet light it fluoresces a vivid blue, sometimes with a greenish cast. This effect is attributed to polycyclic aromatic hydrocarbons — principally perylene — embedded in the resin matrix, which absorb ultraviolet radiation and re-emit it as blue visible light. Dominican blue amber commands a substantial premium in both collector and jewellery markets.

Cherry or red amber, sometimes called cherry amber, has historically been associated with Baltic sources and was particularly fashionable in Victorian jewellery. Much material sold as cherry amber in antique markets is in fact early phenolic resin (Bakelite), and careful testing is essential when purchasing older pieces.

Major Sources and Their Characteristics

Baltic amber is by far the world's largest source, with the principal deposits concentrated along the shores of the Baltic Sea — most notably in the Kaliningrad Oblast of Russia (formerly Königsberg, Prussia), where industrial-scale mining has operated since the nineteenth century, and along the coasts of Poland, Lithuania, Latvia, and Estonia. Baltic amber is found both in primary deposits ("blue earth" glauconitic sands of Eocene age) and as secondary beach deposits, where wave action erodes coastal cliffs and deposits amber on the shoreline. The latter has been collected by hand for millennia and remains a seasonal activity along the Sambian Peninsula. Baltic amber is the benchmark for succinite and dominates global amber jewellery production.

Dominican amber is mined from sedimentary deposits in the Cordillera Septentrional mountains of the northern Dominican Republic, with the Santiago and Puerto Plata regions being the most productive. It is notably clearer and more transparent than much Baltic amber, and its Miocene-age deposits are rich in insect and plant inclusions. The blue amber variety from the El Valle and Palo Quemado mines is internationally renowned. Dominican amber is generally softer and more brittle than Baltic amber, requiring careful handling in lapidary work.

Burmese amber (burmite) is mined in Hukawng Valley, Kachin State, Myanmar. Its Cretaceous age — approximately 99 million years — means that its inclusions represent life forms from the age of dinosaurs, including feathered dinosaur material, early flowering plants, and a remarkable diversity of insects and arachnids not found in younger ambers. Burmite has become one of the most intensively studied amber deposits in palaeontology, with hundreds of new species described from inclusions since the early 2000s. Gemmologically, burmite is typically darker — reddish-brown to near-black — with a higher specific gravity than Baltic amber (approximately 1.034–1.085) and a different infrared absorption spectrum. The trade in burmite has attracted significant ethical scrutiny owing to the conflict context of Kachin State mining operations.

Mexican amber from Chiapas is closely related to Dominican amber in botanical origin and geological age. It tends toward deeper golden and reddish tones and is worked locally into beads, pendants, and small carvings, with a strong domestic craft tradition among indigenous communities of the Simojovel region.

Inclusions

Amber's capacity to entomb and preserve organic matter with extraordinary fidelity is unmatched in the geological record. As fresh resin oozed from tree bark, small organisms — insects, spiders, mites, nematodes, plant fragments, feathers, and even small vertebrates — became trapped and were encapsulated before the resin hardened. Over geological time, the soft tissues of these organisms were replaced or preserved in remarkable detail, sometimes retaining original colour, surface texture, and three-dimensional form.

In the gem trade, inclusions are a primary value driver. A piece of Baltic amber containing a well-preserved insect — particularly a rare or scientifically significant species — may command prices many times that of equivalent clean material. Inclusions of multiple organisms, or of organisms engaged in behavioural interactions (predation, mating), are especially prized. The term inclusion amber is used in the trade to describe material selected and valued specifically for its biological contents.

Gemmological laboratories assess inclusions for authenticity, since the market for amber with inclusions has attracted significant fraud. Common deceptions include drilling a cavity into a piece of amber or copal, inserting a modern insect, and resealing the cavity with resin or adhesive. Detection methods include microscopic examination of the resin flow patterns around the inclusion (genuine inclusions show undisturbed flow lines), infrared spectroscopy to identify the host material, and in some cases computed tomography (CT) scanning. The GIA and Lotus Gemology laboratories have published protocols for inclusion amber authentication.

Treatments and Simulants

Amber is subject to several treatments that affect its appearance and value, and the market contains numerous simulants that require careful identification.

Heating and clarification: Cloudy or "bony" amber can be clarified by heating in rapeseed or linseed oil under controlled conditions, which fills the gas bubbles responsible for opacity. This process may also produce characteristic disc-shaped stress fractures known as sun spangles or lily pads, which are sometimes considered decorative. Heated amber may also develop deeper colour. Clarification is a long-established and widely accepted treatment in the trade, but should be disclosed.

Colour enhancement: Heating in a reducing atmosphere can produce green or deeper reddish colours. Surface coatings are occasionally applied to alter colour or lustre.

Pressed amber (ambroid): Small fragments and chips of genuine amber are ground and fused under heat and pressure to produce larger pieces. Pressed amber, also called ambroid or reconstructed amber, is genuine amber material but is significantly less valuable than natural amber. It can be identified microscopically by characteristic flow structures and elongated bubbles, and by its behaviour under polarised light, which shows strain patterns absent in natural amber.

Copal: As noted above, sub-fossil copal is frequently sold as amber, particularly in tourist markets in East Africa (Zanzibar copal), Madagascar, and Colombia. The brine flotation test, solubility in acetone, and infrared spectroscopy reliably distinguish copal from true amber.

Plastics and glass: Phenolic resins (Bakelite, Catalin), polystyrene, and other synthetic polymers have been used to simulate amber since the early twentieth century. Glass simulants are denser (specific gravity above 2.0) and will sink in brine. Plastics may float but are distinguished by infrared spectroscopy, by the absence of fluorescence typical of amber, and by their behaviour when a hot needle is applied — plastics produce a sharp chemical odour, while amber produces a pleasant, resinous, pine-like smell.

Historical and Cultural Significance

Amber has been traded, carved, and venerated across cultures for at least ten thousand years. The ancient trade routes along which Baltic amber moved south to the Mediterranean — the so-called Amber Road — were among the earliest long-distance commercial networks in European prehistory, and amber beads have been recovered from Bronze Age sites across central Europe, Greece, and the Near East. In ancient Rome, amber was a luxury commodity; Pliny the Elder devoted considerable attention to it in his Naturalis Historia, noting that a small amber figurine could command a higher price than a living slave.

In East Asia, amber — particularly the deep red variety — has been used in Buddhist prayer beads, court jewellery, and decorative objects for centuries, with significant quantities of Baltic amber reaching China via overland trade. The Qing dynasty court maintained a particular appreciation for amber carvings.

The most celebrated amber artefact in history is the Amber Room, originally installed in the Catherine Palace near St Petersburg, constructed in the early eighteenth century using approximately six tonnes of carved and gilded Baltic amber panels. Dismantled by German forces during the Second World War and subsequently lost, the Amber Room has been reconstructed in the Catherine Palace using traditional techniques, a project completed in 2003.

In the Trade

Amber is sold by weight (grams or carats), by piece, or — for high-quality inclusion material — by the significance and condition of the inclusion itself. Baltic amber dominates the global supply and is the benchmark for pricing of standard jewellery-grade material. Dominican blue amber and high-quality burmite with significant inclusions occupy the premium end of the market.

Gemmological testing for amber should include specific gravity determination (brine flotation), ultraviolet fluorescence, infrared spectroscopy (FTIR), and, where inclusions are present, microscopic examination. FTIR is the definitive method for distinguishing amber from copal, pressed amber, and plastic simulants, and is offered by major gemmological laboratories including the GIA and Gübelin Gem Lab.

The ethical sourcing of burmite has become a significant trade issue. Several major scientific journals and institutions have adopted policies restricting the publication of research based on newly acquired burmite owing to concerns about conflict financing in Kachin State, and some auction houses have introduced provenance requirements for Burmese amber lots.

Care and Handling

Amber's softness and organic nature require careful handling. It is vulnerable to scratching by metal, abrasives, and even prolonged contact with skin oils and cosmetics. Prolonged exposure to strong light, heat, and low humidity can cause surface crazing and colour change over time. Amber jewellery should be stored separately from harder gem materials, cleaned with a soft damp cloth, and kept away from ultrasonic cleaners, steam, and chemical solvents. With appropriate care, amber is a stable and durable material for jewellery use.

Further Reading

• GIA Gem Encyclopedia: Amber
• Gems & Gemology: Dominican Amber Notes
• Lotus Gemology: Burmese Amber (Burmite)
• International Gem Society: Amber