This is an Arabia Finland pattern you don’t see very often called “Pallas”.
It is very delicate china, with an equally intricate and delicate stylised floral pattern in gold.
The design is by Raija Uosikkinen, and produced c 1965-1970.
As far as I can tell it was a series of cups, saucer and plates – but not a complete dinner setting.
The sides of the cup are ribbed or scalloped – like a sea shell, which adds to the delicacy and overall feel of the design.