Start with weight and warmth
Amber has a density of roughly 1.05–1.10 g/cm³, which is remarkably low for a material that reads as stone. A 12 mm amber bead in the palm feels wrong to anyone accustomed to glass or agate — noticeably lighter than the eye predicts. This single impression eliminates most glass and resin imitations in under a second.
It also warms fast. Amber reaches skin temperature within seconds of being held, where glass and most stones stay cool for far longer. Neither test is conclusive alone, but together they narrow the field enough to be worth doing first.
The saltwater test
Dissolve roughly 25 grams of salt into 200 ml of water. Genuine amber floats in the resulting brine; most plastics, glass and pressed imitations sink. This is the oldest field test in the trade and it remains useful for a loose bead.
The limitation is obvious: you cannot run it on a finished strand with metal furniture and a silk tassel. Ask a supplier for two loose beads from the same batch precisely so you can test destructively without damaging the sample.
Inspect the inclusions under magnification
Under a 10× loupe, natural amber shows irregular gas bubbles of varying size, occasional plant debris, and internal fracture planes that catch light at inconsistent angles. Imitations show suspiciously regular spherical bubbles, swirl patterns from injection moulding, or a complete absence of internal structure.
Pressed amber — genuine amber reconstituted under heat and pressure — is the difficult case. It shows characteristic elongated bubbles and faint flow lines between the fused fragments. It is genuine amber, and for many commercial programmes it is the correct material. It simply must not be sold as natural.
The two tests that settle it
Under long-wave UV light natural Baltic amber fluoresces a distinct milky blue-white. Most plastics remain inert or fluoresce a dull, even yellow. This is fast, non-destructive and works through a finished strand.
For anything above a certain order value, however, the only answer that survives a dispute is a gemmological laboratory report. FTIR spectroscopy identifies amber unambiguously and distinguishes natural from pressed. If a supplier resists arranging one, you have learned what you needed to know.
What to require from a supplier
Ask for a written material declaration on every order stating natural, pressed or reconstituted. Ask for origin documentation. Ask whether they will arrange third-party verification at your cost. A supplier confident in their material agrees to all three without hesitation.
The suppliers who create problems are the ones who answer the question about treatment with a description of quality instead. Those are not the same subject, and the substitution is deliberate.