Lemon amber is a Baltic-trade colour descriptor for amber displaying a clean pale to medium greenish yellow, distinct from the warmer cognac, butterscotch and honey grades, and from the opaque white and royal grades. It is one of the standard merchant categories used in the Polish and Lithuanian wholesale market, where finished pieces and rough are routinely separated by colour for pricing and matching.

Material and origin

Amber is a fossilised tree resin from the conifer Pinus succinifera and related extinct species. Baltic amber, the dominant commercial source, formed roughly 35-50 million years ago in the Eocene and is recovered from the Sambian Peninsula in the Russian Kaliningrad oblast and along the southern Baltic coast. Approximately 90 per cent of the world's gem-grade amber is mined at Yantarny in Kaliningrad, with smaller production from Poland, Lithuania, Ukraine and Denmark. The chemical composition is broadly C, H and O, with a defining 3-8 per cent succinic acid content that distinguishes Baltic amber (succinite) from copal and from amber of other origins.

Colour origin and treatment

Natural lemon-yellow tones occur in clarified amber and reflect the original resin chemistry along with subsequent geological history. Most commercial amber is autoclave-treated: heated under pressure in an inert atmosphere or in oil, which clarifies cloudy material, can shift colour and induces the characteristic sun spangles (disc-shaped internal stress fractures). Untreated lemon amber tends to be slightly less transparent and more variable in tone than autoclaved goods. Treatment is industry-standard and is generally disclosed on the packaging at wholesale level; at retail, it should be stated on invoice.

Identification

Amber has a refractive index of approximately 1.54, a specific gravity of 1.05-1.10 (it floats in saturated saltwater - a useful field test against plastic imitations, which sink), and a hardness of around 2-2.5 on the Mohs scale. Under longwave ultraviolet, Baltic amber commonly fluoresces a pale chalky bluish white. Infrared spectroscopy is the laboratory standard for distinguishing Baltic succinite from younger copal and from pressed amber (ambroid), where smaller pieces have been heated and compressed.

Trade and use

Lemon amber is used extensively in beaded necklaces, bracelets and small carvings, and is a staple of the Gdansk and Kaliningrad workshops. Prices are modest by gem standards - a good cabochon retails in the tens of dollars rather than hundreds - but matched strands of clean, well-clarified lemon beads command higher figures, and large untreated rough is collected by specialists. As with all amber, buyers should ask whether the piece is natural amber, pressed amber (ambroid) or reconstructed, and whether it has been autoclaved.