18ct white gold
(or is it!)

When you look in the jewellers showcase at white gold 99% of what you see has been rhodium plated.
The rhodium will wear away on rings quite quickly leaving them a rather dull cream/brown colour.

The Garden Workshop only uses a high white gold for its diamond rings.
The gold has been alloyed with 13% palladium to give a white gold that needs no plating and will always look white.