dunno what it means can you help with this old brooch

by stephen hall
(new zealand)

i have this brooch that was my grandmas and even may have been her grandmas too. It has 3 diamonds in it and 4 rubys, if they are rubys, and on the back it has these markings, in order

M&V 15 625 then a anchor and the letter o or b or d?


can you plz help me with this- sorry there will be no photo as my camera can not take a clear photo.