Questions to ask the seller if you still desire to purchase a Rolex off of the internet:
Ask the seller for the serial number of the Rolex watch that you are interested in purchasing. The serial number will tell you the type of watch, year and month made, type of metal (gold, stainless, etc,)
Ask the seller is the watch 100% authentic. If a Rolex watch has non genuine parts, Rolex dealers will not service the watch.
Ask the seller if you can purchase the watch with your credit card. Never purchase a Rolex item from a seller who only wants to sell the watch with a money orders or cashiers checks. Most credit cards have a 90 day fraud protection plan to get your money back if the watch comes up fake or non genuine. Have the watch appraised ASAP. This will help you get your money back with the credit card companies.