- A solitaire ring is a very classic ring style. Often seen for engagement rings, solitaire rings feature a band with a single gemstone set above the band in a prong setting.
- Carat is an abstract tile laying German style board game designed by Dirk Henn and published in 1993 by Queen Games and db Spiele. In 2004, after the success of Alhambra, Queen Games released an updated version of the game with an Arabian theme called Die Gärten der Alhambra.
- A unit of weight for precious stones and pearls, now equivalent to 200 milligrams
- karat: the unit of measurement for the proportion of gold in an alloy; 18-karat gold is 75% gold; 24-karat gold is pure gold
- a unit of weight for precious stones = 200 mg
- one: the smallest whole number or a numeral representing this number; "he has the one but will need a two and three to go with it"; "they had lunch at one"
- one: used of a single unit or thing; not two or more; "`ane' is Scottish"
- "?1" (read "Infinity Ichi"; translated as "Infinity 1") is Do As Infinity's twenty-first single, released on June 17, 2009. The band had disbanded in September 2005, but reformed three years later in September 2008.