بسم الله الرحمن الرحيم
(1) According to the Shari’ah, the zakah of the jewelry which your wife owns is fardh on your wife after passage of one year. It is not fardh on you to pay its zakah. Yes, if you pay the zakah of the said jewelry as a wakil of your wife then the zakah shall be paid.
(2) Zakah is not wajib on dress, no matter how costly they are.
Allah knows Best!
Darul Uloom Deoband