Large Bond Boyd Sterling Pin

This is a large, about 3 inches, vintage Bond Boyd sterling pin. I love the design, but I have no idea how old it might be.

The pin is missing one blue rhinestone. I have matching pink replacement ones - but I don't feel I should change the colour of the stones. Any ideas?

Thanks to davyd286 I found a website selling replacement stones I might order the correct stones from.

Thanks for looking:)