delft plate 1850

[lesday1]

hi can anyone shed any light on the makeer of this plate i think it is delft and dated 1850.
the pattern is clematis but i can`t make out the initials.
it has a pressed mark new stone ? but this is not very clear and what looks like a three leaf clover.
i hope someone can help me with this querry .
thanks and all the best les