Many thanks, Bob. I can comfortably give the coin the reference Sear 1813 now. 
My wife had been doing a bit of research on the web and found the following:
"Some of Basil II's coins do feature a crescent, such as the AR miliaresion coin that has a "pellet in crescent" as part of the cross design.
Significance: While not a universal feature on all of his coinage, the inclusion of symbols like the crescent could have had religious or symbolic meaning, though the exact significance would need further research for each specific coin type."
So the meaning of the crescent remains obscure.
My wife had been doing a bit of research on the web and found the following:
"Some of Basil II's coins do feature a crescent, such as the AR miliaresion coin that has a "pellet in crescent" as part of the cross design.
Significance: While not a universal feature on all of his coinage, the inclusion of symbols like the crescent could have had religious or symbolic meaning, though the exact significance would need further research for each specific coin type."
So the meaning of the crescent remains obscure.





















