Can you help me to identify this coin, can you also tell me a price value for this coin in case if I decide to sell it?
Thank you,
Jovica
Coin side1
Coin side2

Greek inscription says "King Demetrios". Hope this will help!

I think your coin is the following:

KINGS of MACEDON. Demetrios I Poliorketes, The Antigonid dynasty. 306-283 BC. AR Tetradrachm, Chalkis mint. Struck circa 290-287 BC.

Diademed and horned head right / BASILEWS DHMHTRIOU, Nude Poseidon standing left, right foot on rock, holding trident in left hand; monograms to outer left and right.

similar to this one:





If the coin is authentic its a rather expensive coin to wear as a pendant.

If the reverse was a bit larger one could see the monograms to the left and right better.

Thanks for help, I really apriciate.
Jovica

That is a coin duh









sorry I couldn't resist...

It does look cast