Early Cameron Highlanders silver pin--AGE? USE?

[grimble-nibitz]

This came in a lot of early British militaria here in Western Pennslyvania, USA. Its 3 inches tall and is pretty heavy, hand engraved lettering to front, if this was antique jewelry I would date it to 1870 considering the pin style and rat tail open catch...is this a kilt or sash pin, and if so, can anyone tell me its age and rarity, or even value? I cannot find ANYTHING online about this thing and have owned it long enough to be sick to death of my own ignorance about it! Thanks to those whose time has been spent acquiring answers to our questions!