Roman ring with monogram

[cot b]

Have anybody any ideas about  the monogram of thesee ring?

[Aarmale]

Looks like the second monogram stamp is right.  Maybe ?  The style remids my not of Roman, but of Byzantine, but that may not be right.

[chassid-80]

i think that this monogram is for  , in ancient greek for "good luck". the ring may be roman, dating about at 3th - 4th century. Antonio.

[cot b]

Thank's alot!