William IV Monogram ?

[RicercaAraldica]

Dear all,

I kindly ask you a suggestion for the monogram dispalyed on below picture, the monogram says "CW" and has a marquis crown. Since William IV name was Wilhelm Carl Heinrich Friso, and he was maquis of Veere and Vlissingen, I think that this could be his monogam, but I would like to hear a comment from an expert.

http://s30.postimg.org/588zfze1t/Monogramma.jpg

Thanks and Regards