Men wearing white gold
Pure platinum, which is unanimously permissible, is sometimes called white gold. The two metals have nothing in common except for the name which is used for platinum figuratively.
What is legally prohibited for men to wear is the known yellow gold (the component which has the atomic number 79 and the atomic weight 196, 967 in the periodic table). Rulings are contingent upon objects and not their names.
The term white gold may be used to refer to yellow gold alloyed with palladium or other metals. The permissibility of this type of gold is disputed amongst scholars. Therefore, it is better for men to refrain from using itsince it is treated like the known yellow gold (by some scholars).
Based on this, if what is intended by white gold is "Platinum" then it is unanimously lawful. However, if it is a bar of palladium or another metal and yellow gold, then it is better for men to exercise religious caution and refrain from [wearing anything made from] this alloy.
Allah the Majestic knows best