Quality watches with famous name brands, such as Omega, Longines, Cartier, to name only three, are prestigious watches. The most famous of all is Rolex. The best advice I can offer someone looking for a fine watch with a famous name brand is....
a) to get stainless steel or solid gold, not gold plated. Titanium and Platinum are also used to make watch cases and bands.
b) I prefer the mechanism to have been made by that famous name brand. I would not, for example, buy a Longines with an Ebauche mechanism unless the price were low enough. However, very few famous name brands manufacture their own watches any more (Rolex is one).
c) Either buy from a reputable person or be sure to open the watch and inspect the mechanism yourself. There are too many fakes around.
d) Buying a solid gold watch with diamonds or other precious stones is more complicated. You are buying more than a watch: these watches are jewelry. Knowing how to determine whether the watch is real gold and has real diamonds is essential.
Here is a fine Omega Constellation 551 certified chronometer (circa 1960):
Below is a Rolex 1570 certified chronometer (circa 1970), an exceptionally fine watch. There are several noteworthy differences between this Rolex and the Omega above. The "Rolex Oyster" case that houses the mechanism has a screw-down crown and its design overall offers superior protection to the mechanism, particularly against moisture. The Omega has a micrometric regulator, whereas the Rolex is free-sprung, which means that it has no regulator for adjusting the timekeeping. Adjustments are made to the timing screws on the balance wheel. While the free-sprung design is superior in theory, timekeeping is much more difficult to adjust in practice because the balance wheel must be taken out every time in order to avoid breaking a pivot, even when the "Microstellar" adjusting tool is used. The Omega does not have timing screws on the balance wheel. The Rolex has a Breguet Hairspring, which means that the outer coil has an overcoil, allowing the hairspring to expand and contract evenly in all directions. The Omega has a flat hairspring without overcoil. This Rolex cost much more than the Omega, and you can see the differences in the escapement. (Another difference is that the automatic winding rotor in the Rolex 1570 has jewelled bearings, whereas the one in the Omega 551 has a bronze bearing.)
New watches simply cannot replace the elegance of this fine classic Longines (14k white gold and five matching diamonds) with the "Mystery Hour Hand." It has a superb mechanism, made by Longines, circa 1955.