O ring:
• refers to major gasket(s) used in the water resistance treatment of a watch case.
• the patented outermost ring in the case design of XOskeleton watches.

Oscillation: In a mechanical watch, the movement of the balance and spring assembly in both directions, to and fro. In a quartz watch, the double vibration of the quartz. One oscillation comprises two vibrations.

Oscillating weight: another term for "rotor"

P

Palladium: Extremely hard white metal. In some luxury watches it is used instead of nickel in the composition of white gold.

Perpetual: A type of calendar that automatically adjusts for months of different lengths and indicates February 29 in each leap year. Very coveted and expensive complication when found in a mechanical watch.

Plating: Coating a metal base with another metal. In watch making a stainless steel base is coated with gold or other material, the thickness of which can vary from 1-3 microns to 20 microns thick, depending on budget.

Platinum: One of the rarest precious metals, platinum is also one of the strongest and heaviest, making it a popular choice for setting gemstone jewelry and watches. It has a rich, white luster, and an understated look. Platinum is hypoallergenic and tarnish resistant, and when used in jewelry and watches is at least 85 to 95 percent pure. Many platinum watches are produced in limited editions due to the expense and rarity of the metal.

Polished: Brilliant metal surface obtained on the watch-case with fine abrasive.

Power reserve:
• The time the watch will run with a fully charged power supply. For mechanical watches it is usually 36-44 hours, though there are extreme times in some very expensive mechanicals. For quartz watches it can vary from 18 moths to 10 years.
• A complication installed on some mechanical watches which illustrates the estimated amount of operating hours remaining in the tension of the mainspring, shown in a small subdial usually similar to a fuel gauge.

PVD: Physical Vapor Deposition. Method of coating thin watch cases by integrating titanium particles and then depositing gold for color.

Q

Quartz: A natural or commercially synthesized silicon dioxide crystal. used in "quartz analog" or solid state digital watches. when activated by a battery or solar power, the thin sliver of crystal very predictably vibrates at an extremely high frequency (32,768 times per second) thus providing very accurate timekeeping. The main components are: an Electric Circuit Block (Quartz Oscillator and CMOS-IC) and the Mechanical Block (step motor, gear train, hands) and a battery.

Quartz movement: Watch movement which employs the vibrations of a tiny crystal (see "quartz") to maintain accuracy of time. A digital quartz has very few mechanical parts and is powered by a battery. The cell battery must be replaced about every 2 years.

R

Rattrapante: The split seconds chronograph which has two seconds hands sitting atop one another. On depression of a third chronograph button (most chronographs have two), the flyback hand will stop in order to measure say, a lap time; repressing this button with cause the flyback hand to catch up to, or "flyback" to the other seconds hand which has remained in motion.

Ratchet bezel ring: A bezel ring which can either turn one way (known as a unidirectional bezel, and usually moves counter clockwise) or both ways and generally clicks into place.

Red gold: see "rose gold". This deeper color is largely found in Russian productions.

Register: Another name for a sub-dial; this is usually a dial within the main dial of a watch. The best example is possibly a chronograph where there may be registers for the chronograph minutes and hours. Some watches have registers with pointers showing the day and date.

Regulating Elements: Set of parts comprising the regulating system (sprung balance) and the escapement (escape wheel, lever and roller).

Repeater: Watch that strikes the hours by means of a mechanism activated by a push-piece or bolt. There are various types of repeaters. Quarter-repeater: sounding a low note for the hours and a "ding-dong" for each of the quarters; Five-minute repeater: striking the hours, quarters and five-minute periods after the quarter; Minute-repeater: striking the hours, quarters and minutes; Grande sonnerie (grand strike): striking the hours and quarters automatically and repeating when a push-piece is pressed down; Chiming repeater: in which the quarters are struck on three or four gongs of different pitch.

Retrograde: Used to describe a pointer hand on a watch dial (often a sub-dial) which returns to zero at the end of a prescribed period. For example a watch may have retrograde date - in this case the hand moves up a scale a day at a time, pointing to the current date - when it reaches 31 it will spring back to 1. These sub-dials are usually fan shaped.

Rose (or pink) gold: A softly hued gold that contains the same materials as yellow gold but with a higher concentration of copper in the alloy. A popular color in Europe, rose gold in watches is often seen in retro styling or in tricolor gold versions. Some 18k red gold watches achieve their color from additional copper in the alloy.

Rotor: Offset weighted disc of heavy metal, which is made to rotate inside the case of an automatic watch by the energy produced by the movements of the wearer's arm. Its weight tends always to bring it back to the vertical position. De-multiplied by a specially designed device, its rotations continually wind the mainspring of the watch.