UV light and amber

Under long-wave UV (365 nm) most amber fluoresces a milky blue-white or blue-green; Dominican and some Mexican amber glow strongly blue even in daylight. Copal — sub-fossil resin a few hundred to a few million years old — fluoresces weakly white or not at all, and turns tacky under a drop of acetone or alcohol, which true amber resists. Plastics and phenolic resins fluoresce in other colours or not at all, and give a chemical smell under a hot needle rather than the resinous smell of amber.

UV also shows work. Filled cracks, glued joins and modern resin cladding fluoresce differently from the surrounding amber; polished surfaces read evenly while unpolished skin looks dull and mottled. Insects that were embedded in modern resin and then aged show a crisp boundary between two resins. Look at the piece under UV from several angles before you buy.

Baltic amber is defined by succinic acid; “pressed amber” (ambroid) is small pieces fused under heat and pressure, legal to sell as such, and identifiable by flow lines and flattened bubbles. Heat-clarified and “sun-spangled” amber has been heated in oil to clear it and produce disc-shaped stress fractures; both are treatments to disclose.

Storage: amber is soft (Mohs 2–2.5), crazes with heat and dryness, and darkens under UV and daylight. Keep it out of direct sun and away from heat sources, wrap it in soft, unbuffered tissue rather than acid-free buffered paper, and never in a sealed box with silica gel — extremely dry air cracks it.

Myanmar (Burmese) amber carries an ethical and, in some countries, a sanctions problem: its mining funded armed groups after 2017 and several societies asked members not to publish on material acquired after that date. Record the acquisition date and the seller for every piece.