Platignum Bijou Date?

[Cluedoh]

Anyone know when Platignum issued their Bijou pens? I was given one by my mother, she says it was her mothers ie my Nana.

So I have a little family history but can't find any on the pen.

I would like to know whether Platignum date coded their pens and for what years they made the Bijou.

 

Pinkish mottled barrel with gold top

Thanks in anticipation