I’ll never understand why would someone splash out £90,000 on a wedding ring. Even if you’re a supermodel. 
The wedding ring Kate got for herself is said to be a diamond and platinum band based on the Egyptian symbol for long life from London’s exclusive Garrard jewelers. A source said:

“Kate is the main breadwinner in this relationship and has paid for her own ring. She went to Garrard and looked at its selection and a ‘ring visitor’ went to her home to show her designs. She wants the wedding plans tied up by 1 May.”