Ming-Chi Kuo is back with Apple predictions and expects the 2018 iPhone range to pack several new color options including blue, red, gold and orange. The new colors will vary according to model, with the gold color reserved for the 2018 iPhone X sequel.
https://www.notebookcheck.net/Ming-Chi-Kuo-2018-iPhones-could-also-come-in-blue-red-gold-and-orange.315294.0.html