Baltic amber is considered the highest quality in the world. But because amber is a lightweight organic fossil resin, it is possible to imitate using lightweight plastics and synthetics. Some imitations are made with the purpose of creating false insect inclusions, rather than creating a false piece of amber in general. There are a few tests one can do to determine real amber from imitations.
A substance known as copal is an immature resin and is sometimes passed off as amber. It is said to be immature because not all the volatile terpenes have left the resin via geological processes over millions of years. Therefore it is younger in age than true amber and will not stand up to the following tests. Plastics and other synthetics such as celluloid and bakelite will also react differently to these tests than amber.
Plastics are the most common amber imitations and can be distinguished from natural amber. Celluloid is a trademarked thermoplastic, composed of cellulose nitrate and camphor. Amber imitators of celluloid and glass can be distinguished from amber by the fact that when rubbed the imitation does not become as electrostatically charged and gives off the odor of camphor. Amber becomes electrostatically charged when rubbed and like plastic both are warm to the touch and can be distinguished from glass, which is cool to the touch, heavier and has a higher specific gravity. In the lab, amber and imitations can be tested with infrared spectroscopy and/or mass spectrometry. The following tests are the most commonly available and easiest to perform. However care should be taken to avoid damage to the piece in question.
This is the simplest and safest test. Amber is warm to the touch and when rubbed, it will become electrostatically charged and will attract lint/dust particles. This is what the ancient Greeks discovered and named it "electron", which is where we get the term "electricity".
The immature resin copal, and plastic fake amber will deteriorate when in contact with a solvent. Plastics are quickly attacked by alcohol (95% ethyl alcohol), acetone (100%), and ether. A few drops of acetone (fingernail polish remover) or alcohol dripped over the surface of the piece will reveal if it holds up to the solvent. If the surface becomes tacky, it's not amber. Amber will not feel tacky or dissolve under these solvents.
Amber will float or be buoyant in seawater. This is why it washes up on the beaches of the Baltic after a storm. Salt-saturated water (about 2.5 tablespoons per 1 cup water) will show that imitations of amber will sink in salt water.
Amber heated will produce a whitish smoke and smell like burning pine wood, sweet and pleasant. This is why amber has been used by ancient civilizations as incense for many centuries. Amber is identified from plastic imitations with a hot point test (hot needle held with tweezers). When the hot point touches the suspected amber in an unobtrusive place, the material will burn and give off an odor. (Plastics= a disinfectant type odor of camphor or carbolic acid, Amber= burning pinewood). The hot point will make the plastic sticky and leave a black mark. The hot point will make amber brittle and chip off. When celluloid is dipped in hot water or heated, it gives off the odor of camphor. Other plastics give off the unpleasant smell of carbolic acid and no smoke.