Ancient Byzantine Empire gold coin pendant depicting Justin II, 565 - 578 AD.  Gold Solidus, Constantinople mint, 6th officina.  Struck 567 - 578 AD.  

Front:  Helmeted and cuirassed bust facing, holding Victory globe and shield, DN IVSTINVS PP AVG.

Back:  Constantinopolis seated facing, head right, holding spear and globus cruciger, VICTORIA AVGGG-E; CONOB. 

Coin is 21mm in diameter.