K

Karat - indicates the purity of a metal on a scale of 24.  24K (24/24) indicates pure metal. Pure gold is too soft to use in jewelry so it is mixed with another metal. 18K gold means that the alloy is 18 parts gold and 6 parts some other metal. 
        
        18K - gold is also expressed as .750 (750/1000) or 75% pure.
        14K - gold (.555) is 14 parts gold and 10 parts some other metal.  
        10K - gold (.425) is 10 parts gold and 14 parts some other metal.
 

Keeper - the one or two loops on a watch strap that hold the part of the strap that protrudes beyond the buckle.

Kif - a method of shock protection. see incabloc

Kinetic - A quartz movement that does not use a battery.  Energy is stored for a period of time through movement of the wrist that charges a capacitor.