Amber is solidified resin of conifers. Baltic Amber formed 50 million years ago during Eocene epoch, when the massive subtropical forests were growing in The Baltic Sea Catchment Basin. Fallen resin with the lapse of time has naturally solidified and deteriorated into amber due to processes of oxidation and polymerization. Most of it have been collected by the running rivers and drifted to the Baltic Sea. Plants, insects and other wildlife tailings have been adhered to the drifting resin. Plants and organisms inside amber are called inclusions. It is believed that during Eocene epoch subtropical forests could produce 100,000 tons of amber. Baltic Amber consist a great amount of succinate (amber acid), therefore it is called succinite.

Glass
It is heavier, harder, colder and incombustible.

Copal
Generally it is young resin (1000 to 1 million years). Melting temperature is low comparing to amber. It may also have natural inclusions, but usually they are falsified.

Phenolic resin
It is a synthetic resin. Generally these beads are identical to each other in shape, color and looks ‘too perfect’.

Celluloid
it is regarded to be the first thermoplastic. Usually it is yellow and cloudy and looks similar to the amber.

Casein
it is a plastic made from cows milk. A little heavier than amber and have cloudy, turbid yellow color.

Modern plastics
Optically this substitute can hardly be distinguished because with it authentic amber colors and limpidity can be obtained.

There are many various ways to identify true amber. Flotation test "Hot needle" test are two ways which are the most suitable for domestic conditions. Please read following answers where I will explain how to use these methods.

Mix 15ml of table salt with 100ml of water. Dissolve salt in water by stirring. As salt is completely dissolved, drop the piece of amber into the mixture. Note that some additional components of jewellery such as string, fastener etc. can drown the amber due to big weight. Amber, copal and some sorts of plastic should float in such mixture whereas glass and other plastics sink.

Take a needle and heat it over the flame (use pincers to avoid skin burns). Stick a heated needle into an imperceptible place in amber. Copal and amber diffuses definite pine-tree resin smell whereas other sorts of fake amber (plastic etc.) will smell like burning plastic. However, amber is fragile and it does not melt. Sticking with a hot needle you will notice some cracks, while a needle will pierce plastic and copal without cracking it. The “hot needle” test is the most effective way to identify true amber and it does not require any sophisticated equipment. The only negative of this test is the slight mark of burning remains which is irreparable.