Here is a package of wallpaper border by Ralph Lauren. The pattern is Amber Coast Porcelain, 64RL-0209. It would look great with about any of those indigo-blue-and-white Ralph Lauren textiles. There is no amber color in this wallpaper - that's apparently just the name of the collection or something. I don't know why they do that!
If you look at the second image, you will see some suggested coordinating paint colors. Just in case you can't read that tiny print, they are Country Stove White WH05B, River Rapids WH03C, Carson Blue SF05D and Bellflower Blue CO11C.
The wallpaper is 6.83 inches tall and 5 yards long.
I bought this paper secondhand, but it is unused and still wrapped.
The wallpaper is prepasted, but you should plan to supplement that with your own adhesive.
Please send me any questions you may have, and thanks for looking!