...OR it could also be something like:
S D P ............... maybe, since all the letters could become one symbol ??
I googled those letters and came up with SDP

= San Padres Portrait Glass, and also ( LOL ) San padres Pottery ( which yours is not ) so maybe something like that.....
but no ID yet, but TRIED !!!!!! maybe something from :" Santo Domingo " as in SD.mind you could be anything............so NO CLUE AT ALL !!
What is that partial label on it ?? Or symbok there ?