As most people know, amber is a fossilized resin from coniferous trees. It has many amazing magical and healing properties.
Copal is "immature" amber. It's softer and easier to damage, but has most of the same qualities as amber, just to a lesser degree.
 
How to test your jewelry to see whether it is really made of amber:

Light test

True Amber will fluoresce blue under a black light. This is probably the easiest way to tell, with no chance of harm to a piece.

Static test

Another simple and safe test. But probably a lot harder to do if it's a piece set in metal. Amber is warm to the touch and when rubbed, it will become electro-statically charged and will attract lint/dust particles. And to a lesser degree, Copal will do the same.


Solvent test

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.

Buoyancy test

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.

Heat test

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.


Be wary of reconstituted Amber!

If you see several shiny disks inside the "Amber" it is more than likely reconstituted or imitation. These are uncommon in natural Amber as they are actually droplets of water that dispersed creating the little disks and are "frozen" inside. Inclusions of animals can be added to this process. Natural Flora and Fauna inclusions are naturally rare, more so these days.