Hi Louise, you need to look closely at the style and shape of the date letter, in this case, "X" together with the shape of shield or reserve behind where the date letter appears. Identifying the shield is just as important as identifying the date letter.
As only you can see these things, I would like to suggest you determine the date letter by closely comparing the date letter on your gold jewelry with the Birmingham date letters over at at the *** British Gold Council - the Link is on This Page.
If you have any problems Louise downloading the pdf from that page please let me know.