18-karat gold (18KT) is an alloy comprised of 75% of gold and 25% of
other metals.
Depending on the proportion of the other metals mixed with the
gold, the 18-karat gold is classified into three colors such as yellow gold (YG),
white gold (WG) and pink gold (PG).
Decoloration of 18-karat gold
While gold can maintain its glittering quality, other metal components in the alloy may discolor to look like reddish or blackish due to various reasons.
Daily care helps to prevent discoloration of the alloy, however, if the discoloration or stain of the alloy persists even after wiping the watch off, take your watch to the retailer from whom the watch was purchased for refinishing. (Refinishing will be done at a cost.)