Above we have some wedding bands made with different coloured white metals. From left to right: polished titanium, hammered + matte palladium white gold, polished nickel white gold, matte palladium white gold.
Most white gold in North America has nickel because it costs less and creates a very white metal, but nickel allergies develop through exposure to nickel, and wearing a nickel bearing white gold ring can contribute to an allergy. For this reason, nickel is not allowed to be used in jewellery in Europe, and I personally don't recommend it. If you do choose nickel white gold, opt for 18 karat over 10 or 14 karat because 18 karat has more pure gold and is less likely to cause allergies.
The other option is palladium white gold, which has (you guessed it!) palladium. It is a rare metal that is closely related to platinum. It creates a slightly more grey gold, but does not contain nickel.
Titanium is a good, small budget option, but it is not recommended for people that work with their hands. If you were to have an accident (knock on wood) and the finger swells with your ring on, titanium is very hard to cut off. In terms of colour, titanium is the most grey.
If you have any questions about gold options send an email and I'd be happy to help!