Rough amber is rarely available as pieces larger than the palm of the hand. Bakelite and early plastic imitations also can easily fool the buyer. There are several tests one can make to determine the authenticity of a piece. A hot needle and smell test can separate the plastics from the pressed or real amber. Finally, the eye and experience test, to determine pressed vs. natural amber.
Natural swirls are looser and broader.
The placement and visibility of the inclusions is of prime importance. Most pieces of amber are small, and insects are not commonly centrally placed. Also, stress from the death struggle often weakens the integrity of a piece, and internal fractures may be present. Small gnats and flies and ants are most common inclusions in amber. Fairly common are larger ants, small termites, wood boring beetles, stingless bees and varieties of beetles and plant hoppers.