D

Damascening - Decorating metal with inlaid threads of gold or silver. The inlay forms an intricate pattern on a contrasting background. Or, producing a watered effect in forging on metal objects.

Date Display - display of date on the dial of a watch.

Day/Date watch - a watch that indicates the day of the week as well as the date.

DAYLIGHT SAVINGS TIME - adopted around the time of World War l. The purpose is to be able to utilize more of the daylight hours in the spring and summer for daytime activities. It was also seen as a fuel saving measure. Daylight Savings Time is usually 1 hour ahead of Standard Time from April to October.

Demi-hunter Case - has a lid over the dial with an opening in the centre so the time can be read without having to open the lid.

Deployant Buckle - (boucle deployante)

a buckle that fastens to the watch strap and opens and fastens using hinged extenders. Invented by Louis Cartier in 1910. A deployant buckle is easier to put on and remove than a strap.
Deployant comes from the verb "deployer" which means to unfold. Sometimes mistakenly referred to as a "deployment" clasp.

Depth Alarm - alarm on a diver's watch that sounds when the wearer exceeds a pre-set depth. Alarm stops when the diver ascends above the pre-set depth.

Dial – The face of the watch showing the hours, minutes and sometimes seconds.

Digital Display – Time is shown by using digits (numbers) instead of hands and a dial.

Direct Drive - the seconds hand advances in intervals rather than a smooth, sweeping motion.

Display Back - a caseback that is transparent so that the movement may be viewed.

Divers Watch - a watch that is specially constructed for underwater diving.

Doppelchrono (French: Rattrapante) also Split Seconds - 2 seconds hands on a chronograph. When a button is pushed, the 2 hands start together and move in unison. When the button is pushed a second time one of the hands stops to allow the time to be noted and the other seconds hand continues to time the event, thus “splitting” the hands. A third push of the button makes the seconds hand that was stopped “catch up” to the hand that is still moving and once again the 2 hands move in unison.
Example: You want to time how long it takes a racing car to complete 4 laps but you also want to record the time at the end of each lap. At the end of each lap push a button and stop one of the seconds hands to record the time. The other seconds hand continues timing. Another push of the button starts the hands moving in unison once again.

Dual-time-zone - A watch that measures local time as well as time in another time zone. The additional time may come from a twin dial, extra hand or a subdial. Sometimes the additional time is expressed in military fashion, on a 24-hour, rather than 12-hour, basis.