The iPhone 5S went on sale Friday in eleven countries and territories around the world. The gold-colored model, shown here, is already back-ordered online. 
The latest additions to the iPhone line -- the colorful iPhone 5C, left, and higher-end iPhone 5S -- mark the first time Apple has launched two new versions of the phone. Initial reviews have been positive. 
The iPhone 5S is the flagship version of the handset and is available in silver or "space gray" as well as gold. The phone is made from hard-coated polycarbonate, is less than 1/3 of an inch thick and weighs about four ounces. 
The camera on the iPhone 5S has a 15% larger sensor to let in more light and shoot sharper images. A burst mode, for photographing moving targets, lets the user shoot up to 10 photos per second. And, for the first time, video can be played in slow motion. 
The iPhone 5S features Touch ID, a fingerprint scanner that users may use to replace a passcode. Reviewers say that, while it may seem gimmicky, the feature is actually a nice upgrade. 
The Siri voice-activated "digital assistant" feature has been updated. Siri can now adjust iPhone settings, do Bing searches and look through Twitter. It also is now available with a male voice in the U.S.. 
The iPhone 5S's A7 processing chip is the first 64-bit chip to be installed in a smartphone. Apple used the new video game, "Infinity Blade III," to show off its speed, which they say can render images and video as fast as a PC or gaming console. 
The cheaper iPhone 5C ($99) is, largely, an iPhone 5 with a new plastic casing. It's available in five colors -- green, blue, yellow, pink and white. - Apple is facing tight supplies of the new iPhone 5S, reports say
- The gold-hued model is not available online until October
- Phones went on sale Friday in the U.S., Australia, Canada, China, the UK and other nations
(CNN) -- When it comes to new iPhones, bling is the thing.
Early buyers of the iPhone 5S, which went on sale Friday morning, appear to be overwhelmingly choosing the gold-colored model over the two other color options.
People trying to buy a gold phone in Apple's online store Friday saw a message stating the phone will not ship until October. By contrast, Apple said the silver and "space gray" models will be shipped in 7 to 10 business days. That's true for all three varieties of the phone, with 16GB, 32GB, and 64GB of storage.
Anecdotal reports from lines of shoppers outside Apple stores Friday also showed big demand for the gold-hued phones, which Apple is offering for the first time.
"It's new and shiny," explained Georgia Tech student Chance Shafor, 22, who was the first in line Friday morning outside an Apple store at Lenox Square mall in suburban Atlanta. Shafor said he was planning to get the gold version, as were most of the other buyers interviewed outside the store by CNN.
Apple has already asked its suppliers to increase production of the gold (it's really more like champagne-colored) model to meet demand, according a report in the Wall Street Journal.
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Unlocking the new iPhone In China, the iPhone 5S has been available for preorder since Tuesday. Chinese news outlets reported that retailers have already sold all of the gold iPhone 5S models they had in stock. Gold is a wildly popular color in China and India, countries where Apple is hoping to capture a larger slice of the smartphone market.
Unlike past models of the iconic smartphone, the iPhone 5S does not come in black or white.
"Gold is a popular choice in many markets, particularly in Asia where Apple has a stated goal of growth," said Massimiliano Pogliani, CEO of luxury phone company Vertu, in a recent e-mail to CNN. "Gold is a colour that is always in demand, whether for jewelry, watches or fashion."
It's not clear whether any confused buyers think the iPhone 5S actually comes in real gold instead of its gold-colored aluminum. Deep-pocketed Apple fans can actually buy an 18k gold-plated iPhone 5 from luxury retailer Stuart Hughes for 22,000 British pounds, or about $35,000.
The iPhone 5S went on sale Friday in 11 countries and territories along with the iPhone 5C, a cheaper, plastic-encased model that comes in five bright colors. The higher-end 5S has and upgraded camera, faster processor and a new fingerprint sensor for improved security.
Apple could be facing tight supplies of the iPhone 5S. According to 9to5Mac and AllThingsD, sources from U.S. carriers are reporting that their stock of the phones is limited. According to All Things D, AT&T will reserve the gold and silver models for its online sales.
Unlike the 5S, the cheaper iPhone 5C was available for presale online, and so far Apple, wireless carriers and other vendors still have the devices in stock in the U.S. Apple has not released any numbers on pre-orders.
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The phones went on sale Friday in the United States, Australia, Canada, China, France, Germany, Hong Kong, Japan, Puerto Rico, Singapore and the United Kingdom.
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Gene Munster, an analyst at Piper Jaffray, predicts that Apple will sell between and 6 million iPhones around the world during the three-day launch weekend and that it will sell out of iPhone 5S devices completely. He said that Apple will likely move 3 million iPhone 5C models over the weekend.
Some suspect the anticipated sellout is a reason Apple did not make the iPhone 5S available for presale online.
