What does 1 ks on ring mean?

"1 ks on ring" typically refers to a measurement indicating that a ring has a weight of 1 karat (ks is often shorthand for "karat" in specific contexts). In jewelry, a karat is a unit of weight used to measure gemstones and pearls, where 1 karat is equivalent to 200 milligrams. Therefore, a ring marked as "1 ks" would indicate that it contains a gemstone or diamond weighing one karat.