1860 Parkinson & Frodsham 18ct Gold Pocket Watch

• Carat - A carat (abbreviated "ct") is a unit of measurement used to describe the weight of a diamond or other gemstone, and separately is a unit of measurement used to describe the weight of precious metals such as gold,.
  
  For gemstones, one carat is equal to 0.2 grams or 200 milligrams. The weight of a diamond is one of the Four Cs (along with cut, colour, and clarity) that are used to determine a diamond's value.
  
  It is important to note that a diamond's weight does not necessarily correspond to its size. A diamond's cut, which affects how well it reflects light, can make a diamond of a lower weight appear larger than a diamond of a higher weight. Additionally, the carat is not the only factor to determine the value of a diamond, other factors such as clarity, colour and cut are important too.
  
  In the gold industry, the purity of gold is measured in carats (abbreviated "ct"), with 24 karats being pure gold and lower carat numbers indicating a lower purity level. So, for example, 18 carat gold is 18/24 or 75% pure gold, and 12 carat gold is 12/24 or 50% pure gold.
• Circa - A Latin term meaning 'about', often used in the antique trade to give an approximate date for the piece, usually considered to be five years on either side of the circa year. Thus, circa 1900 means the piece was made about 1900, probably between 1895 and 1905. The expression is sometimes abbreviated to c.1900.
• Movement - The technical name for the workings of a clock or watch, and does not include the dial or case.
• Fusee - The fusee movement was used in clocks and pocket watches from the mid 17th century. The fusee is a cone shaped drum within the works that is linked to the barrel of the spring, usually by a length of chain.
  
  As the mainspring loses its tension over time, the cone shaped barrel compensates for this by increasing the tension, by pulling the mainspring tighter, thus ensuring the time remains constant.
  
  Use of the fusee in clocks was superseded by the "going barrel" in the mid 19th century and for pocket watches at the beginning of the 19th century.
  
  The fusee continued to be used in marine chronometers until the 1970s.

This item has been included into following indexes:

• Frodsham, Charles (London) - clocks and watches 28
• pocket watches, case type - open face, gold / gold-plated case 1,339