The Swiss watch movements show the time in Tokyo, Moscow, Paris, London and New York, whilst the sixth can be programmed to the owner's preference.
As well as the unique time features, the iPhone 4 Time Machine also boasts shockproof mineral glass housing with a diamond coating.
Other features include a body fabricated with ultra strong and ultra-lightweight titanium alloy, polished steel, black PVD-coated finish and Italian leather.
Scheduled to go on sale later this year, the phone is expected to cost in the region of $6,000.
Founded in 2005, Gresso provides direct sales of its luxury mobile phones and accessories in 20 countries.