Hi there. It appears to be an item marked in the UK. The "WN" in a diamond is what's known as the sponsor mark, and it's the initials of the firm or indiviual who submitted the piece for marking.
The anchor on its side is the town mark for Birmingham.
the 375 mark is the standard mark. 9Ct gold is the most hard wearing. The price of gold has quadrupled over the last ten years.
the "u" is a date letter, which changes every year.
You might like to to try Researching British Hallmarks. There is a link on that page that leads to Birmingham Maker's Marks & Date Letters. You know it is Birmingham immediately because of the anchor - halve way home :-)
