Hi - The 'pip' illustrated seems to be a base of silver plate which would suggest a pre 1908 Volunteer officer. The colours you speak of relate to the arm or service under which the officer serves - Line Infantry, Corps, etc. but, in essence, the 'pip' follows the insignia device of the Order of the Bath - I have even seen 'pips' advertised as insignia of the Order - the world is full of idiots ! The subject is very wide but essential study for anyone wishing to know precisely what it is they have. Yours, incidentally, is a very nice one - do you have others of the same ? Regards. David