In Hong Kong, it’s all about the gold iPhone 5S. Apple has asked its suppliers to increase production of the gold-colored iPhone 5S by an additional one-third after seeing strong demand, people familiar with the situation said. It isn’t clear whether there are currently supply constraints manufacturing the new iPhone. An Apple spokeswoman declined to comment. Matthew Ng, a 22-year-old university student, stayed up all night earlier this week to make an online reservation for an iPhone 5S to replace his aging iPhone 4. He wanted to order one with a gold color, but he says it was sold out on Apple’s Hong Kong website so he went for a silver one instead. The gold model seems to be the most popular among consumers who placed pre-orders for the iPhone 5S at stores run by Hong Kong’s telecommunications carriers in the city’s Wanchai district earlier this week.